diff --git a/fastNLP/core/utils.py b/fastNLP/core/utils.py
index c9a89f90..b672be77 100644
--- a/fastNLP/core/utils.py
+++ b/fastNLP/core/utils.py
@@ -45,25 +45,38 @@ def pickle_exist(pickle_path, pickle_name):
     else:
         return False
 
-def build_args(func, kwargs):
-    assert isinstance(func, function) and isinstance(kwargs, dict)
+def build_args(func, **kwargs):
     spect = inspect.getfullargspec(func)
-    assert spect.varargs is None, 'Positional Arguments({}) are not supported.'.format(spect.varargs)
+    if spect.varkw is not None:
+        return kwargs
     needed_args = set(spect.args)
-    output = {name: default for name, default in zip(reversed(spect.args), reversed(spect.defaults))}
+    start_idx = len(spect.args) - len(spect.defaults)
+    output = {name: default for name, default in zip(spect.args[start_idx:], spect.defaults)}
     output.update({name: val for name, val in kwargs.items() if name in needed_args})
-    if spect.varkw is not None:
-        output.update(kwargs)
-
-
-# check miss args
-def check_arg_dict(func, arg_dict):
-    pass
-
-def check_arg_dict_list(func, arg_dict_list):
-    pass
-
-def check_code():
-    pass
+    return output
 
+from collections import namedtuple, Counter
+CheckRes = namedtuple('CheckRes', ['missing', 'unused', 'duplicated'], verbose=True)
 
+# check args
+def check_arg_dict_list(func, args):
+    if isinstance(args, dict):
+        arg_dict_list = [args]
+    else:
+        arg_dict_list = args
+    assert callable(func) and isinstance(arg_dict_list, (list, tuple))
+    assert len(arg_dict_list) > 0 and isinstance(arg_dict_list[0], dict)
+    spect = inspect.getfullargspec(func)
+    assert spect.varargs is None, 'Positional Arguments({}) are not supported.'.format(spect.varargs)
+    all_args = set(spect.args)
+    start_idx = len(spect.args) - len(spect.defaults)
+    default_args = set(spect.args[start_idx:])
+    require_args = all_args - default_args
+    input_arg_count = Counter()
+    for arg_dict in arg_dict_list:
+        input_arg_count.update(arg_dict.keys())
+    duplicated = [name for name, val in input_arg_count.items() if val > 1]
+    input_args = set(input_arg_count.keys())
+    missing = list(require_args - input_args)
+    unused = list(input_args - all_args)
+    return CheckRes(missing=missing, unused=unused, duplicated=duplicated)