A method, a system and a device for maintaining user service continuity are provided in an embodiment of the present invention. The method includes prohibiting a UE from accessing a forbidden network before handover is complete when the UE needs to perform network handover if the UE adopts a SIM access technology, thus avoiding service interruption of a SIM user due to access to an incorrect network. A system and a device for maintaining user service continuity are provided in an embodiment of the present invention.