diff --git a/httprunner/loader.py b/httprunner/loader.py
index 482b9ad7..cdc630e5 100644
--- a/httprunner/loader.py
+++ b/httprunner/loader.py
@@ -140,6 +140,24 @@ def load_folder_files(folder_path, recursive=True):
 
 def load_dot_env_file(path):
     """ load .env file
+
+    Args:
+        path (str): .env file path.
+            If path is None, it will find .env file in current working directory.
+
+    Returns:
+        dict: environment variables mapping
+
+            {
+                "UserName": "debugtalk",
+                "Password": "123456",
+                "PROJECT_KEY": "ABCDEFGH"
+            }
+
+    Raises:
+        exceptions.FileNotFound: If specified env file is not exist.
+        exceptions.FileFormatError: If env file format is invalid.
+
     """
     if not path:
         path = os.path.join(os.getcwd(), ".env")
@@ -719,8 +737,13 @@ def load_testcases(path):
 
 def load(path):
     """ main interface for loading testcases
-    @param (str) path: testcase file/folder path
-    @return (list) testcases list
+
+    Args:
+        path (str): testcase file/folder path
+
+    Returns:
+        list: testcases list
+
     """
     if validator.is_testcases(path):
         return path
diff --git a/httprunner/task.py b/httprunner/task.py
index 76746552..58bbd921 100644
--- a/httprunner/task.py
+++ b/httprunner/task.py
@@ -206,7 +206,8 @@ class HttpRunner(object):
             - dot_env_path: .env file path
         """
         dot_env_path = kwargs.pop("dot_env_path", None)
-        utils.set_os_environ(loader.load_dot_env_file(dot_env_path))
+        self.env_mapping = loader.load_dot_env_file(dot_env_path)
+        utils.set_os_environ(self.env_mapping)
 
         kwargs.setdefault("resultclass", HtmlTestResult)
         self.runner = unittest.TextTestRunner(**kwargs)