The present application discloses a method for processing a non-access stratum message, user equipment, and a network side device. The user equipment includes a configuration module, at least one non-access stratum module, and at least two access stratum modules, and the at least two access stratum modules separately support different network standards, where the configuration module is configured to acquire configuration information, and map the at least one non-access stratum module to at least one of the access stratum modules according to the configuration information, so that the at least one non-access stratum module transfers a non-access stratum message with the access stratum module to which mapping is performed. According to the present invention, a technical problem that a mapping relationship between an access stratum and a non-access stratum in prior-art user equipment is fixed can be resolved, signaling interactions can be reduced, and a delay can be shortened.