diff --git a/fastNLP/core/callbacks/progress_callback.py b/fastNLP/core/callbacks/progress_callback.py
index a091a35c..42f703af 100644
--- a/fastNLP/core/callbacks/progress_callback.py
+++ b/fastNLP/core/callbacks/progress_callback.py
@@ -79,7 +79,7 @@ class RichCallback(ProgressCallback):
 
     def on_train_begin(self, trainer):
         self.task2id['epoch'] = self.progress_bar.add_task(description='Epoch:0', total=trainer.n_epochs,
-                                                    completed=trainer.global_forward_batches/(trainer.total_batches+1e-6))
+                                                    completed=trainer.global_forward_batches/(trainer.n_batches+1e-6))
 
     def on_train_epoch_begin(self, trainer):
         self.epoch_bar_update_advance = self.print_every/(trainer.num_batches_per_epoch + 1e-6)
@@ -190,7 +190,7 @@ class RawTextCallback(ProgressCallback):
             self.loss = 0
             text = f'Epoch:{trainer.cur_epoch_idx}/{trainer.n_epochs}, Batch:{trainer.batch_idx_in_epoch}, ' \
                    f'loss:{round(loss, self.loss_round_ndigit)}, ' \
-                   f'finished {round(trainer.global_forward_batches/trainer.total_batches*100, 2)}%.'
+                   f'finished {round(trainer.global_forward_batches/trainer.n_batches*100, 2)}%.'
             logger.info(text)
 
     def on_evaluate_end(self, trainer, results):
@@ -251,7 +251,7 @@ class TqdmCallback(ProgressCallback):
     def on_train_begin(self, trainer):
         self.task2id['epoch'] = self.progress_bar.add_task(description='Epoch:0', total=trainer.n_epochs,
             bar_format='{desc}: {percentage:3.0f}%|{bar}| [{elapsed}<{remaining}, {rate_fmt}, {postfix}]',
-            initial=trainer.global_forward_batches/(trainer.total_batches+1e-6))
+            initial=trainer.global_forward_batches/(trainer.n_batches+1e-6))
 
     def on_train_epoch_begin(self, trainer):
         self.epoch_bar_update_advance = self.print_every/(trainer.num_batches_per_epoch + 1e-6)
diff --git a/fastNLP/core/callbacks/torch_callbacks/torch_lr_sched_callback.py b/fastNLP/core/callbacks/torch_callbacks/torch_lr_sched_callback.py
index 006a39c0..29c1aa2b 100644
--- a/fastNLP/core/callbacks/torch_callbacks/torch_lr_sched_callback.py
+++ b/fastNLP/core/callbacks/torch_callbacks/torch_lr_sched_callback.py
@@ -41,7 +41,7 @@ class TorchWarmupCallback(Callback):
         return max((progress - 1.) / (self.warmup - 1.), 0.)
 
     def on_train_begin(self, trainer):
-        self.t_steps = trainer.total_batches
+        self.t_steps = trainer.n_batches
         if self.warmup >1:
             self.warmup = self.warmup / self.t_steps
         self.t_steps = max(2, self.t_steps)  # 不能小于2
diff --git a/fastNLP/core/controllers/evaluator.py b/fastNLP/core/controllers/evaluator.py
index bafabbe9..a1d4adf8 100644
--- a/fastNLP/core/controllers/evaluator.py
+++ b/fastNLP/core/controllers/evaluator.py
@@ -460,14 +460,15 @@ class _MetricsWrapper:
         for metric in self._metrics:
             args = []
             if not isinstance(batch, dict):
-                logger.warning_once(
+                logger.rank_zero_warning(
                     f"The output of the DataLoader is of type:`{type(batch)}`, fastNLP will only depend on "
-                    f"the output of model to update metric.")
+                    f"the output of model to update metric.", once=True)
             else:
                 args.append(batch)
             if not isinstance(outputs, dict):
                 raise RuntimeError(f"The output of your model is of type:`{type(outputs)}`, please either directly"
-                                   f" return a dict from your model or use `output_mapping` to convert it into dict type.")
+                                   f" return a dict from your model or use `output_mapping` to convert it into dict "
+                                   f"type.")
             if isinstance(metric, Metric):
                 # 这样在 auto_param_call 报错的时候才清晰。
                 auto_param_call(metric.update, outputs, *args, signature_fn=metric.update.__wrapped__)
diff --git a/fastNLP/core/controllers/trainer.py b/fastNLP/core/controllers/trainer.py
index 076f674b..4f6c0dc4 100644
--- a/fastNLP/core/controllers/trainer.py
+++ b/fastNLP/core/controllers/trainer.py
@@ -110,7 +110,7 @@ class Trainer(TrainerEventTrigger):
 
             对于使用 ``TorchDDPDriver`` 的更多细节，请见 :class:`~fastNLP.core.drivers.torch_driver.TorchDDPDriver`。
 
-    :param n_epochs: 训练总共的 epoch 的数量，默认为 20；
+    :param n_epochs: 训练总共的 epoch 的数量，默认为 20；也可以通过 ``n_batches`` 参数设置总共迭代多少个 ``batch`` 。
     :param evaluate_dataloaders: 验证数据集，其可以是单独的一个数据集，也可以是多个数据集；当为多个数据集时，注意其必须是 Dict；默认
         为 None；
     :param batch_step_fn: 定制每次训练时前向运行一个 batch 的数据所执行的函数。该函数应接受两个参数为 ``trainer`` 和 ``batch``，
@@ -237,6 +237,8 @@ class Trainer(TrainerEventTrigger):
 
         注意该参数仅当 ``Trainer`` 内置的 ``Evaluator`` 不为 None 时且有需要该参数但是没有设置该参数的 *callback* 实例才有效；
 
+    :param n_batches: 迭代多少个 ``batch`` 的训练结束。当该值不为 -1 时，将直接忽略 ``n_epochs`` 的值。
+
     :param marker: 用于标记一个 ``Trainer`` 实例，从而在用户调用 ``Trainer.on`` 函数时，标记该函数属于哪一个具体的 ``Trainer`` 实例；默认为 None；
 
         .. note::
@@ -356,6 +358,7 @@ class Trainer(TrainerEventTrigger):
             fp16: bool = False,
             monitor: Union[str, Callable] = None,
             larger_better: bool = True,
+            n_batches: int = -1,
             marker: Optional[str] = None,
             **kwargs
     ):
@@ -426,6 +429,7 @@ class Trainer(TrainerEventTrigger):
             model_wo_auto_param_call=model_wo_auto_param_call,
             accumulation_steps=accumulation_steps,
             fp16=fp16,
+            n_batches=n_batches,
             marker=marker,
             **kwargs
         )
@@ -444,12 +448,12 @@ class Trainer(TrainerEventTrigger):
         # 初始化 state，包括提供给用户的接口和我们自己使用的接口；
         self.state = State()
         self.trainer_state = TrainerState(
-            n_epochs=n_epochs,
+            n_epochs=n_epochs if n_batches!=-1 else None,
             cur_epoch_idx=0,
             global_forward_batches=0,
             batch_idx_in_epoch=0,
             num_batches_per_epoch=None,  # 会在具体的 train_batch_loop 中进行初始化；
-            total_batches=None
+            n_batches=n_batches
         )
 
         if metrics is None and evaluate_dataloaders is not None:
@@ -598,14 +602,18 @@ class Trainer(TrainerEventTrigger):
             self.dataloader = _TruncatedDataLoader(self.dataloader, num_train_batch_per_epoch)
 
         self.num_batches_per_epoch = len(self.dataloader)
-        self.total_batches = self.num_batches_per_epoch * self.n_epochs
+        if self.n_batches == -1:
+            self.n_batches = self.num_batches_per_epoch * self.n_epochs
+        else:
+            self.n_epochs = (self.n_batches+self.num_batches_per_epoch-1)//self.num_batches_per_epoch
+
         self.global_forward_batches = self.num_batches_per_epoch * self.cur_epoch_idx + self.batch_idx_in_epoch
 
         try:
             self.on_train_begin()
             self.driver.barrier()
             self.driver.zero_grad()
-            while self.cur_epoch_idx < self.n_epochs:
+            while self.cur_epoch_idx < self.n_epochs and self.global_forward_batches < self.n_batches:
                 # 这个是防止在 Trainer.load_checkpoint 之后还没结束当前 epoch 又继续 save
                 self.start_batch_idx_in_epoch = self.trainer_state.batch_idx_in_epoch
                 self.driver.set_model_mode("train")
@@ -1367,15 +1375,15 @@ class Trainer(TrainerEventTrigger):
         self.trainer_state.num_batches_per_epoch = num_batches_per_epoch
 
     @property
-    def total_batches(self) -> int:
+    def n_batches(self) -> int:
         r"""
         :return: 返回整体的训练中实际会训练多少个 batch 的数据；
         """
-        return self.trainer_state.total_batches
+        return self.trainer_state.n_batches
 
-    @total_batches.setter
-    def total_batches(self, total_batches: int):
-        self.trainer_state.total_batches = total_batches
+    @n_batches.setter
+    def n_batches(self, n_batches: int):
+        self.trainer_state.n_batches = n_batches
 
     """ driver property """
 
diff --git a/fastNLP/core/controllers/utils/state.py b/fastNLP/core/controllers/utils/state.py
index a8103c62..676b548c 100644
--- a/fastNLP/core/controllers/utils/state.py
+++ b/fastNLP/core/controllers/utils/state.py
@@ -50,7 +50,7 @@ class TrainerState:
     :param global_forward_batches: 当前模型总共 forward 了多少个 step；
     :param batch_idx_in_epoch: 训练中在当前 epoch 的第几个 step；
     :param num_batches_per_epoch: 每一个 epoch 会 forward 多少个 step；
-    :param total_batches: 完整训练过程会 forward 的 step 数量，注意 total_batches = total_batches * n_epochs；
+    :param n_batches: 完整训练过程会 forward 的 step 数量，注意 n_batches = n_batches * n_epochs；
     """
     n_epochs: Optional[int] = None  # 无论如何重新算
 
@@ -61,7 +61,7 @@ class TrainerState:
 
     num_batches_per_epoch: Optional[int] = None  # 无论如何重新算
 
-    total_batches: Optional[int] = None  # 无论如何重新算
+    n_batches: Optional[int] = None  # 无论如何重新算
 
     def state_dict(self) -> Dict:
         r"""
diff --git a/fastNLP/core/dataset/dataset.py b/fastNLP/core/dataset/dataset.py
index a48ddaff..d5b45eeb 100644
--- a/fastNLP/core/dataset/dataset.py
+++ b/fastNLP/core/dataset/dataset.py
@@ -156,7 +156,6 @@ import _pickle as pickle
 from copy import deepcopy
 from typing import Optional, List, Callable, Union, Dict, Any, Mapping
 from types import LambdaType
-from subprocess import DEVNULL
 import sys
 import time
 
@@ -170,6 +169,7 @@ from fastNLP.core.utils.rich_progress import f_rich_progress, DummyFRichProgress
 from fastNLP.core.utils.tqdm_progress import f_tqdm_progress
 from ..log import logger
 from fastNLP.core.utils.dummy_class import DummyClass
+from ..utils.utils import _get_fun_msg
 
 
 progress_bars = {
@@ -780,8 +780,8 @@ class DataSet:
         apply_out = self._apply_process(num_proc, func, progress_desc=progress_desc,
                                         progress_bar=progress_bar)
         #   只检测第一个数据是否为dict类型，若是则默认所有返回值为dict；否则报错。
-        if not isinstance(apply_out[0], dict):
-            raise Exception("The result of func is not a dict")
+        if not isinstance(apply_out[0], Mapping):
+            raise Exception(f"The result of func:{_get_fun_msg(func)} is not a dict, but of type {type(apply_out[0])}")
 
         for key, value in apply_out[0].items():
             results[key] = [value]
@@ -789,7 +789,8 @@ class DataSet:
         try:
             for idx, per_out in enumerate(apply_out[1:]):
                 if len(set(results.keys()) - set(per_out.keys())):
-                    raise ApplyResultException("apply results have different fields", idx + 1)
+                    raise ApplyResultException(f"Apply results have different fields:{set(results.keys())} and "
+                                               f"{set(per_out.keys())}", idx + 1)
                 for key, value in per_out.items():
                     results[key].append(value)
 
diff --git a/fastNLP/core/samplers/reproducible_batch_sampler.py b/fastNLP/core/samplers/reproducible_batch_sampler.py
index edb8a67f..206bf18d 100644
--- a/fastNLP/core/samplers/reproducible_batch_sampler.py
+++ b/fastNLP/core/samplers/reproducible_batch_sampler.py
@@ -169,7 +169,7 @@ class RandomBatchSampler(ReproducibleBatchSampler):
     :param kwargs: fastNLP 保留使用
     """
     def __init__(self, dataset, batch_size:int = 32, shuffle: bool = True,
-                 drop_last: bool = False, seed: int = 0, **kwargs):
+                 drop_last: bool = False, seed: int = None, **kwargs):
         super().__init__()
 
         self.dataset = dataset
diff --git a/fastNLP/core/utils/rich_progress.py b/fastNLP/core/utils/rich_progress.py
index b28bb3f7..013d3775 100644
--- a/fastNLP/core/utils/rich_progress.py
+++ b/fastNLP/core/utils/rich_progress.py
@@ -120,7 +120,7 @@ class FRichProgress(Progress, metaclass=Singleton):
 
     def add_task(
             self,
-            description: str,
+            description: str = 'Progress',
             start: bool = True,
             total: float = 100.0,
             completed: int = 0,
diff --git a/fastNLP/io/file_reader.py b/fastNLP/io/file_reader.py
index 9181bc06..2df61e17 100644
--- a/fastNLP/io/file_reader.py
+++ b/fastNLP/io/file_reader.py
@@ -7,7 +7,7 @@ __all__ = []
 import json
 import csv
 
-# from ..core import log
+from ..core import logger
 
 
 def _read_csv(path, encoding='utf-8', headers=None, sep=',', dropna=True):
@@ -81,7 +81,7 @@ def _read_json(path, encoding='utf-8', fields=None, dropna=True):
             yield line_idx, _res
 
 
-def _read_conll(path, encoding='utf-8',sep=None, indexes=None, dropna=True):
+def _read_conll(path, encoding='utf-8',sep=None, indexes=None, dropna=True, drophash=True):
     r"""
     Construct a generator to read conll items.
 
@@ -91,6 +91,7 @@ def _read_conll(path, encoding='utf-8',sep=None, indexes=None, dropna=True):
     :param indexes: conll object's column indexes that needed, if None, all columns are needed. default: None
     :param dropna: weather to ignore and drop invalid data,
             :if False, raise ValueError when reading invalid data. default: True
+    :param drophash: 是否丢掉以 # 开头的 line 。
     :return: generator, every time yield (line number, conll item)
     """
 
@@ -121,7 +122,7 @@ def _read_conll(path, encoding='utf-8',sep=None, indexes=None, dropna=True):
                             sample = []
                             continue
                         raise ValueError('Invalid instance which ends at line: {}'.format(line_idx))
-            elif line.startswith('#'):
+            elif line.startswith('#') and drophash:
                 continue
             else:
                 sample.append(line.split(sep)) if sep else sample.append(line.split())
diff --git a/fastNLP/io/loader/conll.py b/fastNLP/io/loader/conll.py
index 90045e46..b15d31f7 100644
--- a/fastNLP/io/loader/conll.py
+++ b/fastNLP/io/loader/conll.py
@@ -52,13 +52,14 @@ class ConllLoader(Loader):
 
     """
     
-    def __init__(self, headers, sep=None, indexes=None, dropna=True):
+    def __init__(self, headers, sep=None, indexes=None, dropna=True, drophash=True):
         r"""
         
         :param list headers: 每一列数据的名称，需为List or Tuple  of str。``header`` 与 ``indexes`` 一一对应
         :param list sep: 指定分隔符，默认为制表符
         :param list indexes: 需要保留的数据列下标，从0开始。若为 ``None`` ，则所有列都保留。Default: ``None``
         :param bool dropna: 是否忽略非法数据，若 ``False`` ，遇到非法数据时抛出 ``ValueError`` 。Default: ``True``
+        :param bool drophashtag: 是否忽略以 ``#`` 开头的句子。
         """
         super(ConllLoader, self).__init__()
         if not isinstance(headers, (list, tuple)):
@@ -66,6 +67,7 @@ class ConllLoader(Loader):
                 'invalid headers: {}, should be list of strings'.format(headers))
         self.headers = headers
         self.dropna = dropna
+        self.drophash = drophash
         self.sep=sep
         if indexes is None:
             self.indexes = list(range(len(self.headers)))
@@ -82,7 +84,8 @@ class ConllLoader(Loader):
         :return: DataSet
         """
         ds = DataSet()
-        for idx, data in _read_conll(path,sep=self.sep, indexes=self.indexes, dropna=self.dropna):
+        for idx, data in _read_conll(path,sep=self.sep, indexes=self.indexes, dropna=self.dropna,
+                                     drophash=self.drophash):
             ins = {h: data[i] for i, h in enumerate(self.headers)}
             ds.append(Instance(**ins))
         return ds
diff --git a/tests/core/callbacks/torch_callbacks/test_torch_warmup_callback.py b/tests/core/callbacks/torch_callbacks/test_torch_warmup_callback.py
index ecdaa1c5..4a48cd8b 100644
--- a/tests/core/callbacks/torch_callbacks/test_torch_warmup_callback.py
+++ b/tests/core/callbacks/torch_callbacks/test_torch_warmup_callback.py
@@ -32,4 +32,4 @@ def test_torch_warmup_callback(warmup, schedule, accumulation_steps):
     elif schedule == 'constant':
         assert np.allclose(0.1, kwargs['optimizers'].param_groups[0]['lr'])
 
-    assert len(r_callback.lrs)<=trainer.total_batches//accumulation_steps+1
\ No newline at end of file
+    assert len(r_callback.lrs)<=trainer.n_batches//accumulation_steps+1
\ No newline at end of file
diff --git a/tests/helpers/callbacks/helper_callbacks_torch.py b/tests/helpers/callbacks/helper_callbacks_torch.py
index 4b9730da..9369d009 100644
--- a/tests/helpers/callbacks/helper_callbacks_torch.py
+++ b/tests/helpers/callbacks/helper_callbacks_torch.py
@@ -55,4 +55,4 @@ class RecordAccumulationStepsCallback_Torch(Callback):
 
     def on_train_end(self, trainer):
         print(f"\n equal num: {self.equal}.\n")
-        print(f"\ntotal_batch_num: {trainer.total_batches}.\n")
+        print(f"\ntotal_batch_num: {trainer.n_batches}.\n")