Thank you Peter~ I have resolved my problem after Chris R. Spartz's reply . the port issue causes our problem
I check the wtuser, remoteobjectinfo, remoteobjectid,OwningRepositoryLocalObject tables but I dare not delete the entries of disconnected principals
I wanna delete the invalid users through the Windchill web page,it is safe because the Windchill System will check the user group that the principal in, the workitems and project activities that the user taken before deleteing the user
Thank you for your reply~