A method and system for route optimization during switching and an access network element. In a process that a terminal is switched from a source access network element to a target access network element, the target access network element obtains identity information of a correspondent node of the terminal from the terminal, and triggers an access network element of the correspondent node to update a correspondent node mapping relationship. In the present solution, information of a correspondent node is obtained by adding a signaling interaction procedure between the network and the terminal host, so that the information of the correspondent node which is performing data communication is obtained in real time, and a subsequent data stream route optimization process is performed in time, thereby solving the problem of low processing performance and poor real-time performance resulted from an access gateway monitoring, detecting and maintaining correspondent node information.