仔細一看，SSO返回的ticket也不相同，才發現原來IIS重啟了，最后解決方案如下： 

新建一個類繼承IHttpModule 

復制代碼代碼如下:

/// <summary> 
/// Stops the ASP.NET AppDomain being restarted (which clears 
/// Session state, Cache etc.) whenever a folder is deleted. 
/// </summary> 
public class StopAppDomainRestartOnFolderDeleteModule : IHttpModule 
{ 
private static bool DisableFCNs = false; 
public void Init(HttpApplication context) 
{ 
if (DisableFCNs) return; 
PropertyInfo p = typeof(HttpRuntime).GetProperty("FileChangesMonitor", BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static); 
object o = p.GetValue(null, null); 
FieldInfo f = o.GetType().GetField("_dirMonSubdirs", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.IgnoreCase); 
object monitor = f.GetValue(o); 
MethodInfo m = monitor.GetType().GetMethod("StopMonitoring", BindingFlags.Instance | BindingFlags.NonPublic); 
m.Invoke(monitor, new object[] { }); 
DisableFCNs = true; 
} 
public void Dispose() { } 
} 

隨后在Web.Config中加入Module配置 

復制代碼代碼如下:

<!--解決刪除項目文件/文件夾引起的IIS重啟--> 
<add name="stopAppDomainRestartOnFolderDelete" type="DeployAssistant.Facade.Web.StopAppDomainRestartOnFolderDeleteModule,DeployAssistant.Facade"/> 

這樣每次再刪除文件/文件夾AppDomain都不會重啟了，Session也不會丟失了。世界也變得更美好了！ 

PS：Web.Config和bin文件夾下的改動依然會讓Web重啟，這也是必須保留的！