diff --git a/httprunner/app/routers/debug.py b/httprunner/app/routers/debug.py
index 51dc2276..b4d4fefb 100644
--- a/httprunner/app/routers/debug.py
+++ b/httprunner/app/routers/debug.py
@@ -4,6 +4,7 @@ from httprunner.runner import HttpRunner
 from httprunner.schema import ProjectMeta, TestCase
 
 router = APIRouter()
+runner = HttpRunner()
 
 
 @router.post("/hrun/debug/testcase", tags=["debug"])
@@ -19,9 +20,7 @@ async def debug_single_testcase(project_meta: ProjectMeta, testcase: TestCase):
         for func_name in new_added_keys:
             project_meta.functions[func_name] = locals()[func_name]
 
-    config = testcase.config
-    teststeps = testcase.teststeps
-    runner = HttpRunner(config, teststeps).with_project_meta(project_meta).run()
+    runner.with_project_meta(project_meta).run(testcase)
     summary = runner.get_summary()
 
     if not summary.success:
diff --git a/httprunner/runner.py b/httprunner/runner.py
index 5561c812..bcb8d9c4 100644
--- a/httprunner/runner.py
+++ b/httprunner/runner.py
@@ -1,11 +1,11 @@
 import os
 import time
 from datetime import datetime
-from typing import List, Dict
+from typing import List, Dict, Text
 
 from loguru import logger
 
-from httprunner import utils
+from httprunner import utils, exceptions
 from httprunner.client import HttpSession
 from httprunner.exceptions import ValidationFailure, ParamsError
 from httprunner.loader import load_project_meta, load_testcase_file
@@ -28,9 +28,9 @@ class HttpRunner(object):
     config: TConfig
     teststeps: List[TStep]
 
-    session: HttpSession
+    session: HttpSession = None
     variables: VariablesMapping = {}
-    step_datas: List[StepData] = []
+    step_datas: List[StepData] = None
     validation_results: Dict = {}
     session_variables: Dict = {}
     success: bool = True  # indicate testcase execution result
@@ -132,13 +132,11 @@ class HttpRunner(object):
         step_variables = step.variables
 
         ref_testcase_path = os.path.join(self.project_meta.PWD, step.testcase)
-        _, testcase_obj = load_testcase_file(ref_testcase_path)
-
         case_result = (
             HttpRunner()
             .with_session(self.session)
             .with_variables(step_variables)
-            .run(testcase_obj)
+            .run_path(ref_testcase_path)
         )
         step_data.data = case_result.step_datas  # list of step data
         step_data.export = case_result.get_export_variables()
@@ -175,7 +173,7 @@ class HttpRunner(object):
             self.project_meta = ProjectMeta()
 
         self.start_at = time.time()
-        self.step_datas.clear()
+        self.step_datas: List[StepData] = []
         self.session_variables.clear()
         for step in self.teststeps:
             # update with config variables
@@ -194,6 +192,13 @@ class HttpRunner(object):
         self.duration = time.time() - self.start_at
         return self
 
+    def run_path(self, path: Text) -> "HttpRunner":
+        if not os.path.isfile(path):
+            raise exceptions.ParamsError(f"Invalid testcase path: {path}")
+
+        _, testcase_obj = load_testcase_file(path)
+        return self.run(testcase_obj)
+
     def get_export_variables(self) -> Dict:
         export_vars_mapping = {}
         for var_name in self.config.export:
diff --git a/httprunner/runner_test.py b/httprunner/runner_test.py
index e69de29b..9635ac4f 100644
--- a/httprunner/runner_test.py
+++ b/httprunner/runner_test.py
@@ -0,0 +1,36 @@
+import unittest
+
+from httprunner.runner import HttpRunner
+
+
+class TestHttpRunner(unittest.TestCase):
+    def setUp(self):
+        self.runner = HttpRunner()
+
+    def test_run_testcase_by_path_request_only(self):
+        self.runner.run_path(
+            "examples/postman_echo/request_methods/request_with_variables.yml"
+        )
+        result = self.runner.get_summary()
+        self.assertTrue(result.success)
+        self.assertEqual(
+            result.name, "request methods testcase with variables"
+        )
+        self.assertEqual(
+            result.step_datas[0].name, "get with params"
+        )
+        self.assertEqual(len(result.step_datas), 3)
+
+    def test_run_testcase_by_path_ref_testcase(self):
+        self.runner.run_path(
+            "examples/postman_echo/request_methods/request_with_testcase_reference.yml"
+        )
+        result = self.runner.get_summary()
+        self.assertTrue(result.success)
+        self.assertEqual(
+            result.name, "request methods testcase: reference testcase"
+        )
+        self.assertEqual(
+            result.step_datas[0].name, "request with variables"
+        )
+        self.assertEqual(len(result.step_datas), 1)
diff --git a/httprunner/utils_test.py b/httprunner/utils_test.py
index 2d1cbd17..f5d33be0 100644
--- a/httprunner/utils_test.py
+++ b/httprunner/utils_test.py
@@ -2,7 +2,7 @@ import io
 import os
 import unittest
 
-from httprunner import new_loader, utils
+from httprunner import loader, utils
 
 
 class TestUtils(unittest.TestCase):
@@ -16,7 +16,7 @@ class TestUtils(unittest.TestCase):
     def current_validators(self):
         from httprunner.builtin import comparators
 
-        functions_mapping = new_loader.load_module_functions(comparators)
+        functions_mapping = loader.load_module_functions(comparators)
 
         functions_mapping["equals"](None, None)
         functions_mapping["equals"](1, 1)