A method and a system for implementing a terminal handover are provided and applied to a network with an identity identifier and location separation architecture. An access identifier (AID) is taken as a user identity identifier of a terminal in the network, a routing identifier (RID) is taken as a location identifier of the terminal. The terminal intercommunicates with a correspondent node in the traditional network by an intercommunication gateway ISN (Intercommunication Service Node). The method includes: when the terminal communicates with a correspondent node in a traditional network, a source access node ASN (Access Service Node) being informed that the terminal needs a handover and requesting a target ASN for a handover; the target ASN responding to the request of the source ASN, the source ASN sending the information of the correspondent node of the terminal to the target ASN; after the handover between the source ASN and the target ASN is completed, the target ASN assigning to the terminal a RID pointing to the ASN itself, and sending the updated AID-RID mapping information of the terminal to an ISN through which the terminal communicates with the correspondent node in the traditional network according to the information of the correspondent node of the terminal. The technical scheme can ensure that an interruption caused by a handover does not occur in the on-going communication service between a terminal and a traditional network.