A security implementation method includes receiving, by a first network element, a request for handing over user equipment from a source access network device to a target access network device to perform communication. The method further includes obtaining, by the first network element, a security key, where the security key is used for protecting the communication between the user equipment and the target access network device after the user equipment is handed over from the source access network device to the target access network device, and sending, by the first network element, the security key to the target access network device.