The present invention relates to the technical field of communication networks. Disclosed are a method and device for bearing a circuit switched domain voice service, so as to solve the problems of high cost of LTE for supporting a voice service and large delay in voice service setup. In embodiments of the present invention, a first network device receives, through a first interface, a paging message sent by a second network device, the paging message carrying an ID of a UE; the first network device generates a first message according to the paging message and a UE state corresponding to the ID of the UE and sends the first message to the UE through a second interface, the first message being used to instruct the UE to access a network of a first mode; and the first network device receives a voice service setup request sent by the UE through the second interface, and allocates radio resources of the first mode for bearing a voice service to the UE according to the voice service setup request. The solution provided in the embodiments of the present invention is applicable to bearing a circuit switched domain voice service.