The invention discloses an account opening and registering method which accesses fixed users to an IMS domain, comprising that a user mark is assigned to users and the use mark and the user local domain name mark are written to an attributive customer server; the attributive customer server inserts user data down to a service calling session control function entity by a user data upgrading message; the service calling session control function entity sends a user data upgrading response message back to the attributive customer server, which indicates successful data updating.