A method for processing handover state information, a mobile access gateway (MAG), and a mobile node (MN) are disclosed. The method includes: receiving a handover state notification message, where the handover state notification message includes interface handover indication information; determining a handover indication option value according to the interface handover indication information; and generating and sending a proxy binding update (PBU) message, where the PBU message includes the handover indication option value. With the present invention, a MAG can obtain the handover state information of an MN through the interface handover indication information of the MN. The application scope is wide, and the access success probability is increased; therefore, the access quality of service (QoS) provided for the user is improved.