diff --git a/.github/ISSUE_TEMPLATE/bug_report.md b/.github/ISSUE_TEMPLATE/bug_report.md
index d5dd03b6..348ffe51 100644
--- a/.github/ISSUE_TEMPLATE/bug_report.md
+++ b/.github/ISSUE_TEMPLATE/bug_report.md
@@ -17,6 +17,16 @@ Please complete the following information:
  - OS: [e.g. macos, Linux, Windows]
  - Python [e.g. 3.6]
  - HttpRunner [e.g. 2.1.2]
+- **Device ID**: [e.g. 190070690681122]
+
+How to get device ID?
+
+In Python interactive shell, execute the following command:
+
+```bash
+>>> import uuid; print(uuid.getnode())
+190070690681122
+```
 
 ## Traceback
 
diff --git a/.github/ISSUE_TEMPLATE/bug_report_zh.md b/.github/ISSUE_TEMPLATE/bug_report_zh.md
index 3cb953f2..7099691a 100644
--- a/.github/ISSUE_TEMPLATE/bug_report_zh.md
+++ b/.github/ISSUE_TEMPLATE/bug_report_zh.md
@@ -17,6 +17,16 @@ assignees: debugtalk
  - 操作系统类型: [e.g. macos, Linux, Windows]
  - Python 版本 [e.g. 3.6]
  - HttpRunner 版本 [e.g. 2.1.2]
+ - **设备 ID**: [e.g. 190070690681122]
+
+获取方式：
+
+在 Python 交互式 shell 中输入如下命令进行获取：
+
+```bash
+>>> import uuid; print(uuid.getnode())
+190070690681122
+```
 
 ## 项目文件内容（非必须）
 
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 4a712bbd..058025a2 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -1,5 +1,12 @@
 # Release History
 
+## 2.5.3 (2020-01-03)
+
+**Fixed**
+
+- fix json schema: variables maybe in string type, e.g. '${prepare_variables()}'
+- fix json schema: post json maybe in string type, e.g. '${prepare_post_data()}', '$post_data'
+
 ## 2.5.2 (2020-01-02)
 
 **Fixed**
diff --git a/httprunner/__init__.py b/httprunner/__init__.py
index 75a512bb..7774739f 100644
--- a/httprunner/__init__.py
+++ b/httprunner/__init__.py
@@ -1,4 +1,4 @@
-__version__ = "2.5.2"
+__version__ = "2.5.3"
 __description__ = "One-stop solution for HTTP(S) testing."
 
 __all__ = ["__version__", "__description__"]
diff --git a/httprunner/loader/schemas/common.schema.json b/httprunner/loader/schemas/common.schema.json
index 0cbf6038..ce5a33e4 100644
--- a/httprunner/loader/schemas/common.schema.json
+++ b/httprunner/loader/schemas/common.schema.json
@@ -23,6 +23,14 @@
                         "maxProperties": 1,
                         "minProperties": 1
                     }
+                },
+                {
+                    "type": "string",
+                    "pattern": "^\\$.*",
+                    "examples": [
+                        "${prepare_variables()}",
+                        "${prepare_variables($a, $b)}"
+                    ]
                 }
             ]
         },
@@ -110,8 +118,21 @@
                     ]
                 },
                 "json": {
-                    "description": "request body in json format",
-                    "type": "object"
+                    "oneOf": [
+                        {
+                            "description": "request body in json format",
+                            "type": "object"
+                        },
+                        {
+                            "description": "request body in string format, e.g. '${prepare_json($a, $b)}'",
+                            "type": "string",
+                            "pattern": "^\\$.*",
+                            "examples": [
+                                "$post_data",
+                                "${prepare_post_data($a, $b)}"
+                            ]
+                        }
+                    ]
                 },
                 "headers": {
                     "description": "request headers",
diff --git a/pyproject.toml b/pyproject.toml
index 39fec7ec..be0c6f14 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "httprunner"
-version = "2.5.2"
+version = "2.5.3"
 description = "One-stop solution for HTTP(S) testing."
 license = "Apache-2.0"
 readme = "README.md"