diff --git a/httprunner/report/html/gen_report.py b/httprunner/report/html/gen_report.py
index 95772079..f76c668c 100644
--- a/httprunner/report/html/gen_report.py
+++ b/httprunner/report/html/gen_report.py
@@ -1,6 +1,5 @@
 import io
 import os
-from datetime import datetime
 
 from jinja2 import Template
 from loguru import logger
@@ -19,7 +18,7 @@ def gen_html_report(testsuite_summary: TestSuiteSummary, report_template=None, r
         report_file (str): specify html report file path, this has higher priority than specifying report dir.
 
     """
-    if not testsuite_summary.time or testsuite_summary.stat.testcases["total"] == 0:
+    if testsuite_summary.stat.total == 0:
         logger.error(f"test result testsuite_summary is empty ! {testsuite_summary}")
         raise SummaryEmpty
 
@@ -34,17 +33,13 @@ def gen_html_report(testsuite_summary: TestSuiteSummary, report_template=None, r
 
     logger.info("Start to render Html report ...")
 
-    start_at_timestamp = testsuite_summary.time.start_at
-    utc_time_iso_8601_str = datetime.utcfromtimestamp(start_at_timestamp).isoformat()
-    testsuite_summary.time.start_datetime = utc_time_iso_8601_str
-
     if report_file:
         report_dir = os.path.dirname(report_file)
         report_file_name = os.path.basename(report_file)
     else:
         report_dir = report_dir or os.path.join(os.getcwd(), "reports")
         # fix #826: Windows does not support file name include ":"
-        report_file_name = "{}.html".format(utc_time_iso_8601_str.replace(":", "").replace("-", ""))
+        report_file_name = "{}.html".format(testsuite_summary.time.start_at_iso_format.replace(":", "").replace("-", ""))
 
     if not os.path.isdir(report_dir):
         os.makedirs(report_dir)
diff --git a/httprunner/report/summarize.py b/httprunner/report/summarize.py
index 3234f3eb..773a9c3d 100644
--- a/httprunner/report/summarize.py
+++ b/httprunner/report/summarize.py
@@ -1,4 +1,5 @@
 import platform
+from datetime import datetime
 
 from httprunner import __version__
 from httprunner.report.html.result import HtmlTestResult
@@ -57,10 +58,13 @@ def get_summary(result: HtmlTestResult) -> TestCaseSummary:
             }
 
     """
+    start_at_timestamp = result.start_at
+    start_at_iso_format = datetime.utcfromtimestamp(start_at_timestamp).isoformat()
     return TestCaseSummary(
         success=result.wasSuccessful(),
         time=TestCaseTime(
             start_at=result.start_at,
+            start_at_iso_format=start_at_iso_format,
             duration=result.duration
         ),
         name=result.name,
diff --git a/httprunner/v3/api.py b/httprunner/v3/api.py
index 8b34bfd2..bbce1a64 100644
--- a/httprunner/v3/api.py
+++ b/httprunner/v3/api.py
@@ -151,10 +151,17 @@ class HttpRunner(object):
                 testsuite_summary["stat"]["fail"] += 1
 
             testsuite_summary["success"] &= testcase_summary.success
-            report.aggregate_stat(testsuite_summary["time"], testcase_summary.time.dict())
 
             testsuite_summary["details"].append(testcase_summary)
 
+        total_duration = tests_results[-1].time.start_at + tests_results[-1].time.duration \
+                         - tests_results[0].time.start_at
+        testsuite_summary["time"] = {
+            "start_at": tests_results[0].time.start_at,
+            "start_at_iso_format": tests_results[0].time.start_at_iso_format,
+            "duration": total_duration
+        }
+
         return TestSuiteSummary.parse_obj(testsuite_summary)
 
     def run_tests(self, tests_mapping) -> TestSuiteSummary:
diff --git a/httprunner/v3/schema.py b/httprunner/v3/schema.py
index 11474260..fb48131c 100644
--- a/httprunner/v3/schema.py
+++ b/httprunner/v3/schema.py
@@ -84,8 +84,8 @@ class TestsMapping(BaseModel):
 
 class TestCaseTime(BaseModel):
     start_at: float
+    start_at_iso_format: Text
     duration: float
-    start_datetime: Text = ""
 
 
 class TestCaseInOut(BaseModel):