A multi-card user equipment, and service processing method and device thereof are provided. The method includes, when receiving a service request, detecting whether a data transmission channel has been established with a network, wherein a number of the established data transmission channels is less than a number of the subscriber identity cards in the multi-card user equipment; and processing a service corresponding to the service request by using the established data transmission channel. With the method, multiple cards can be provided service at the same time, while hardware cost and complexity is decreased and wireless transmission resources is saved.