The mobility management network element performs security protection on a paging identity of a terminal device by using a security context obtained by negotiating with the terminal device, to obtain a first paging identity, and sends a first paging message to a base station. The base station sends a second paging message to the terminal device, where the second paging message carries the first paging identity and first indication information, and the first indication information is used to indicate that the first paging identity is a security-protected paging identity. The terminal device performs security verification on the first paging identity by using the security context based on the first indication information, to obtain a second paging identity, and processing the second paging message based on the second paging identity and an identity of the terminal device.