The invention provides a method for processing the mismatching of UE and a network security algorithm, comprising the following steps: a network side receives security capacity information of the UE, judges whether the security capacity information of the UE is matched with the security capacity information supported by a verifying entity or not; if not, a response message is returned to the UE; the response message carries mismatching identification; the UE returns to EMM to register the state or restarts security verification according to the mismatching identification. When the UE is not matched with the network side security algorithm, the invention can switch new MME for the UE, thus improving the access probability of the UE.