An anti-cloning method includes the following steps: 1, SGSN responds to the adhesion required information of a first user to design adhesive identification (ID) for it and keeps it in the text of said user, 2, SGSN inquires all adhesion users to judge if a second user exists having the same international mobile user ID, if so, it continues, otherwise, it responds to the adhesion request of the first user, 3, SGSN verifies if the adhesion ID of the second user is the same, if so, it responds to the requirement of the first user, otherwise, it informs the system users having said international mobile ID are duplicated, which can increase the safety of networks by identifying cloned SIM card with SGSN when two same SIM cards require for adhesion. |