diff --git a/IRaCIS.Core.Domain/Trial/Trial.cs b/IRaCIS.Core.Domain/Trial/Trial.cs
index 2a3812f28..fa45f6f95 100644
--- a/IRaCIS.Core.Domain/Trial/Trial.cs
+++ b/IRaCIS.Core.Domain/Trial/Trial.cs
@@ -359,7 +359,7 @@ namespace IRaCIS.Core.Domain.Models
 
         public int IndicationEnum { get; set; } = -1;
 
-        public string VitrualSiteCode { get; set; }
+        public string VitrualSiteCode { get; set; }=string.Empty;
 
         #region 邮件配置
         /// <summary>