Provided in the embodiments of the present disclosure are a paging method, a network device, and a terminal device. The method includes when a second network device determines that downlink data of a terminal device arrives, a first network device sending a first paging message to the terminal device. The first paging message is used to page the terminal device for the second network device. The first network device is a network device in a first network, the second network device is a network device in a second network, and the first network and the second network are different networks among a plurality of networks registered by the terminal device.