diff --git a/HealthMonitor.WebApi/Controllers/HealthMonitor/HmFetalController.cs b/HealthMonitor.WebApi/Controllers/HealthMonitor/HmFetalController.cs
index b857d56..dc3edbd 100644
--- a/HealthMonitor.WebApi/Controllers/HealthMonitor/HmFetalController.cs
+++ b/HealthMonitor.WebApi/Controllers/HealthMonitor/HmFetalController.cs
@@ -62,7 +62,9 @@ namespace HealthMonitor.WebApi.Controllers.HealthMonitor
             pchr.MaxValue = mockMax;
             pchr.MinValue = mockMin;
             pchr.Remark = remark;   
-            pchr.Timestamp = DateTime.Now;  
+            pchr.Timestamp = DateTime.Now;
+            pchr.SerialTailNumber = sn[^2..];
+
             await _serviceTDengine.InsertAsync<PregnancyCommonHeartRateModel>("hm_pchr", pchr);
             var flag=await _serviceIotApi.SetFetalConfig(pchr.SerialNumber, 1, pchr.MaxValue, pchr.MinValue);
             return new {