Multi-card mobile terminal, and service switching method and device thereof are provided. The method includes: when network mode switch is performed, switching a data transmission channel in a current network mode which performs multi-card service into a data transmission channel in a target network mode; updating a mapping relation between service identification of a corresponding subscriber identity card and the data transmission channel in the current network mode into a mapping relation between the service identification of the corresponding subscriber identity card and the data transmission channel in the target network mode; and performing multi-card service based on the mapping relation between the service identification of the corresponding subscriber identity card and the data transmission channel in the target network mode. For a multi-card mobile terminal which uses a same data transmission channel to perform multi-card service, the multi-card service may be continued when a network mode changes.