diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index ec3fce4a..3206dd26 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -10,6 +10,7 @@
 **Changed**
 
 - change: import locust at beginning to monkey patch all modules
+- change: open file in binary mode
 
 ## 3.1.1 (2020-06-23)
 
diff --git a/httprunner/ext/har2case/utils.py b/httprunner/ext/har2case/utils.py
index 110f8b40..ead83b30 100644
--- a/httprunner/ext/har2case/utils.py
+++ b/httprunner/ext/har2case/utils.py
@@ -27,9 +27,9 @@ def load_har_log_entries(file_path):
             ]
 
     """
-    with open(file_path, encoding="utf-8") as f:
+    with open(file_path, mode="rb") as f:
         try:
-            content_json = json.loads(f.read())
+            content_json = json.load(f)
             return content_json["log"]["entries"]
         except (TypeError, JSONDecodeError) as ex:
             logger.error(f"failed to load HAR file {file_path}: {ex}")
diff --git a/httprunner/loader.py b/httprunner/loader.py
index b389c716..8a28f0ed 100644
--- a/httprunner/loader.py
+++ b/httprunner/loader.py
@@ -28,7 +28,7 @@ project_meta: Union[ProjectMeta, None] = None
 def _load_yaml_file(yaml_file: Text) -> Dict:
     """ load yaml file and check file content format
     """
-    with open(yaml_file, encoding="utf-8") as stream:
+    with open(yaml_file, mode="rb") as stream:
         try:
             yaml_content = yaml.load(stream)
         except yaml.YAMLError as ex:
@@ -42,7 +42,7 @@ def _load_yaml_file(yaml_file: Text) -> Dict:
 def _load_json_file(json_file: Text) -> Dict:
     """ load json file and check file content format
     """
-    with open(json_file, encoding="utf-8") as data_file:
+    with open(json_file, mode="rb") as data_file:
         try:
             json_content = json.load(data_file)
         except json.JSONDecodeError as ex:
@@ -127,17 +127,17 @@ def load_dot_env_file(dot_env_path: Text) -> Dict:
     logger.info(f"Loading environment variables from {dot_env_path}")
     env_variables_mapping = {}
 
-    with open(dot_env_path, encoding="utf-8") as fp:
+    with open(dot_env_path, mode="rb") as fp:
         for line in fp:
             # maxsplit=1
-            if "=" in line:
-                variable, value = line.split("=", 1)
-            elif ":" in line:
-                variable, value = line.split(":", 1)
+            if b"=" in line:
+                variable, value = line.split(b"=", 1)
+            elif b":" in line:
+                variable, value = line.split(b":", 1)
             else:
                 raise exceptions.FileFormatError(".env format error")
 
-            env_variables_mapping[variable.strip()] = value.strip()
+            env_variables_mapping[variable.strip().decode("utf-8")] = value.strip().decode("utf-8")
 
     utils.set_os_environ(env_variables_mapping)
     return env_variables_mapping
diff --git a/httprunner/scaffold.py b/httprunner/scaffold.py
index 07d1f33a..3f42f32d 100644
--- a/httprunner/scaffold.py
+++ b/httprunner/scaffold.py
@@ -49,7 +49,7 @@ def create_scaffold(project_name):
         print(msg)
 
     def create_file(path, file_content=""):
-        with open(path, "w") as f:
+        with open(path, "w", encoding="utf-8") as f:
             f.write(file_content)
         msg = f"created file: {path}"
         print(msg)