diff --git a/docs/requirements.txt b/docs/requirements.txt
index 2809876b..294a44d0 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,4 +1,5 @@
 numpy>=1.14.2
 http://download.pytorch.org/whl/cpu/torch-0.4.1-cp35-cp35m-linux_x86_64.whl
 torchvision>=0.1.8
-sphinx-rtd-theme==0.4.1
\ No newline at end of file
+sphinx-rtd-theme==0.4.1
+tensorboardX>=1.4
\ No newline at end of file
diff --git a/fastNLP/loader/config_loader.py b/fastNLP/loader/config_loader.py
index 20d791c4..94871222 100644
--- a/fastNLP/loader/config_loader.py
+++ b/fastNLP/loader/config_loader.py
@@ -92,8 +92,40 @@ class ConfigSection(object):
         setattr(self, key, value)
 
     def __contains__(self, item):
+        """
+        :param item: The key of item.
+        :return: True if the key in self.__dict__.keys() else False.
+        """
         return item in self.__dict__.keys()
 
+    def __eq__(self, other):
+        """Overwrite the == operator
+
+        :param other: Another ConfigSection() object which to be compared.
+        :return: True if value of each key in each ConfigSection() object are equal to the other, else False.
+        """
+        for k in self.__dict__.keys():
+            if k not in other.__dict__.keys():
+                return False
+            if getattr(self, k) != getattr(self, k):
+                return False
+
+        for k in other.__dict__.keys():
+            if k not in self.__dict__.keys():
+                return False
+            if getattr(self, k) != getattr(self, k):
+                return False
+
+        return True
+
+    def __ne__(self, other):
+        """Overwrite the != operator
+
+        :param other:
+        :return:
+        """
+        return not self.__eq__(other)
+
     @property
     def data(self):
         return self.__dict__
diff --git a/fastNLP/saver/config_saver.py b/fastNLP/saver/config_saver.py
new file mode 100644
index 00000000..e05e865e
--- /dev/null
+++ b/fastNLP/saver/config_saver.py
@@ -0,0 +1,147 @@
+import os
+
+from fastNLP.loader.config_loader import ConfigSection, ConfigLoader
+from fastNLP.saver.logger import create_logger
+
+
+class ConfigSaver(object):
+
+    def __init__(self, file_path):
+        self.file_path = file_path
+        if not os.path.exists(self.file_path):
+            raise FileNotFoundError("file {} NOT found!".__format__(self.file_path))
+
+    def _get_section(self, sect_name):
+        """This is the function to get the section with the section name.
+
+        :param sect_name: The name of section what wants to load.
+        :return: The section.
+        """
+        sect = ConfigSection()
+        ConfigLoader(self.file_path).load_config(self.file_path, {sect_name: sect})
+        return sect
+
+    def _read_section(self):
+        """This is the function to read sections from the config file.
+
+        :return: sect_list, sect_key_list
+            sect_list: A list of ConfigSection().
+            sect_key_list: A list of names in sect_list.
+        """
+        sect_name = None
+
+        sect_list = {}
+        sect_key_list = []
+
+        single_section = {}
+        single_section_key = []
+
+        with open(self.file_path, 'r') as f:
+            lines = f.readlines()
+
+        for line in lines:
+            if line.startswith('[') and line.endswith(']\n'):
+                if sect_name is None:
+                    pass
+                else:
+                    sect_list[sect_name] = single_section, single_section_key
+                    single_section = {}
+                    single_section_key = []
+                    sect_key_list.append(sect_name)
+                sect_name = line[1: -2]
+                continue
+
+            if line.startswith('#'):
+                single_section[line] = '#'
+                single_section_key.append(line)
+                continue
+
+            if line.startswith('\n'):
+                single_section_key.append('\n')
+                continue
+
+            if '=' not in line:
+                log = create_logger(__name__, './config_saver.log')
+                log.error("can NOT load config file [%s]" % self.file_path)
+                raise RuntimeError("can NOT load config file {}".__format__(self.file_path))
+
+            key = line.split('=', maxsplit=1)[0].strip()
+            value = line.split('=', maxsplit=1)[1].strip() + '\n'
+            single_section[key] = value
+            single_section_key.append(key)
+
+        if sect_name is not None:
+            sect_list[sect_name] = single_section, single_section_key
+            sect_key_list.append(sect_name)
+        return sect_list, sect_key_list
+
+    def _write_section(self, sect_list, sect_key_list):
+        """This is the function to write config file with section list and name list.
+
+        :param sect_list: A list of ConfigSection() need to be writen into file.
+        :param sect_key_list: A list of name of sect_list.
+        :return:
+        """
+        with open(self.file_path, 'w') as f:
+            for sect_key in sect_key_list:
+                single_section, single_section_key = sect_list[sect_key]
+                f.write('[' + sect_key + ']\n')
+                for key in single_section_key:
+                    if key == '\n':
+                        f.write('\n')
+                        continue
+                    if single_section[key] == '#':
+                        f.write(key)
+                        continue
+                    f.write(key + ' = ' + single_section[key])
+                f.write('\n')
+
+    def save_config_file(self, section_name, section):
+        """This is the function to be called to change the config file with a single section and its name.
+
+        :param section_name: The name of section what needs to be changed and saved.
+        :param section: The section with key and value what needs to be changed and saved.
+        :return:
+        """
+        section_file = self._get_section(section_name)
+        if len(section_file.__dict__.keys()) == 0:#the section not in file before
+            with open(self.file_path, 'a') as f:
+                f.write('[' + section_name + ']\n')
+                for k in section.__dict__.keys():
+                    f.write(k + ' = ')
+                    if isinstance(section[k], str):
+                        f.write('\"' + str(section[k]) + '\"\n\n')
+                    else:
+                        f.write(str(section[k]) + '\n\n')
+        else:
+            change_file = False
+            for k in section.__dict__.keys():
+                if k not in section_file:
+                    change_file = True
+                    break
+                if section_file[k] != section[k]:
+                    logger = create_logger(__name__, "./config_loader.log")
+                    logger.warning("section [%s] in config file [%s] has been changed" % (
+                        section_name, self.file_path
+                    ))
+                    change_file = True
+                    break
+            if not change_file:
+                return
+
+            sect_list, sect_key_list = self._read_section()
+            if section_name not in sect_key_list:
+                raise AttributeError()
+
+            sect, sect_key = sect_list[section_name]
+            for k in section.__dict__.keys():
+                if k not in sect_key:
+                    if sect_key[-1] != '\n':
+                        sect_key.append('\n')
+                    sect_key.append(k)
+                sect[k] = str(section[k])
+                if isinstance(section[k], str):
+                    sect[k] = "\"" + sect[k] + "\""
+                sect[k] = sect[k] + "\n"
+            sect_list[section_name] = sect, sect_key
+            self._write_section(sect_list, sect_key_list)
diff --git a/test/loader/config b/test/loader/config
index a1922d28..b91e750d 100644
--- a/test/loader/config
+++ b/test/loader/config
@@ -1,7 +1,18 @@
 [test]
 x = 1
+
 y = 2
+
 z = 3
+#this is an example
 input = [1,2,3]
+
 text = "this is text"
+
 doubles = 0.5
+
+[t]
+x = "this is an test section"
+
+[test-case-2]
+double = 0.5
diff --git a/test/loader/test_loader.py b/test/loader/test_loader.py
index d2f22166..740ff952 100644
--- a/test/loader/test_loader.py
+++ b/test/loader/test_loader.py
@@ -33,18 +33,16 @@ class TestConfigLoader(unittest.TestCase):
 
         test_arg = ConfigSection()
         ConfigLoader("config").load_config(os.path.join("./test/loader", "config"), {"test": test_arg})
-        # ConfigLoader("config").load_config("/home/ygxu/github/fastNLP_testing/fastNLP/test/loader/config",
-        #                                       {"test": test_arg})
 
-        #dict = read_section_from_config("/home/ygxu/github/fastNLP_testing/fastNLP/test/loader/config", "test")
-        dict = read_section_from_config(os.path.join("./test/loader", "config"), "test")
+        section = read_section_from_config(os.path.join("./test/loader", "config"), "test")
 
-        for sec in dict:
-            if (sec not in test_arg) or (dict[sec] != test_arg[sec]):
+
+        for sec in section:
+            if (sec not in test_arg) or (section[sec] != test_arg[sec]):
                 raise AttributeError("ERROR")
 
         for sec in test_arg.__dict__.keys():
-            if (sec not in dict) or (dict[sec] != test_arg[sec]):
+            if (sec not in section) or (section[sec] != test_arg[sec]):
                 raise AttributeError("ERROR")
 
         try:
@@ -71,4 +69,4 @@ class TestDatasetLoader(unittest.TestCase):
         loader = LMDatasetLoader("./test/data_for_tests/cws_pku_utf_8")
         data = loader.load()
         datas = loader.load_lines()
-        print("pass TokenizeDatasetLoader test!")
+        print("pass TokenizeDatasetLoader test!")
\ No newline at end of file
diff --git a/test/saver/test_config_saver.py b/test/saver/test_config_saver.py
new file mode 100644
index 00000000..45daf0c6
--- /dev/null
+++ b/test/saver/test_config_saver.py
@@ -0,0 +1,82 @@
+import os
+
+import unittest
+import configparser
+import json
+
+from fastNLP.loader.config_loader import ConfigSection, ConfigLoader
+from fastNLP.saver.config_saver import ConfigSaver
+
+
+class TestConfigSaver(unittest.TestCase):
+    def test_case_1(self):
+        config_file_dir = "./test/loader/"
+        config_file_name = "config"
+        config_file_path = os.path.join(config_file_dir, config_file_name)
+
+        tmp_config_file_path = os.path.join(config_file_dir, "tmp_config")
+
+        with open(config_file_path, "r") as f:
+            lines = f.readlines()
+
+        standard_section = ConfigSection()
+        t_section = ConfigSection()
+        ConfigLoader(config_file_path).load_config(config_file_path, {"test": standard_section, "t": t_section})
+
+        config_saver = ConfigSaver(config_file_path)
+
+        section = ConfigSection()
+        section["doubles"] = 0.8
+        section["tt"] = 0.5
+        section["test"] = 105
+        section["str"] = "this is a str"
+
+        test_case_2_section = section
+        test_case_2_section["double"] = 0.5
+
+        for k in section.__dict__.keys():
+            standard_section[k] = section[k]
+
+        config_saver.save_config_file("test", section)
+        config_saver.save_config_file("another-test", section)
+        config_saver.save_config_file("one-another-test", section)
+        config_saver.save_config_file("test-case-2", section)
+
+        test_section = ConfigSection()
+        at_section = ConfigSection()
+        another_test_section = ConfigSection()
+        one_another_test_section = ConfigSection()
+        a_test_case_2_section = ConfigSection()
+
+        ConfigLoader(config_file_path).load_config(config_file_path, {"test": test_section,
+                                                                      "another-test": another_test_section,
+                                                                      "t": at_section,
+                                                                      "one-another-test": one_another_test_section,
+                                                                      "test-case-2": a_test_case_2_section})
+
+        assert test_section == standard_section
+        assert at_section == t_section
+        assert another_test_section == section
+        assert one_another_test_section == section
+        assert a_test_case_2_section == test_case_2_section
+
+        config_saver.save_config_file("test", section)
+
+        with open(config_file_path, "w") as f:
+            f.writelines(lines)
+
+        with open(tmp_config_file_path, "w") as f:
+            f.write('[test]\n')
+            f.write('this is an fault example\n')
+
+        tmp_config_saver = ConfigSaver(tmp_config_file_path)
+        try:
+            tmp_config_saver._read_section()
+        except Exception as e:
+            pass
+        os.remove(tmp_config_file_path)
+
+        try:
+            tmp_config_saver = ConfigSaver("file-NOT-exist")
+        except Exception as e:
+            pass