The invention provides a method for updating user data and a system to carry out the method. The method for updating user data comprises the following steps that user data management equipment receives a reset message sent by user location management equipment, and the reset message carries the identification information of the user location management equipment; the user data management equipment sends a request to insert user data to the user location management equipment according to the identification information so as to control the data to be used for updating the user location management equipment and the request for inserting user data carries the user data which is needed to be inserted by the user management equipment. With the adoption of the technical proposal provided by the invention, the user data management equipment can be prevented from being overloaded after the user management equipment is resumed from failure.