A method and system for fast handover in hierarchical mobile IPv6 includes: a mobile node which transmits a proxy route request message to a previous access router of the mobile node according to a handover expectation provided by the link layer, the previous access router transmits a network prefix information of a new access router of the mobile node to the mobile node; the mobile node which generates new care-of address according to the network prefix information; after the mobile node moves to a target network, an optimistic duplicate address detection is performed on the care-of address. The disclosure can simplify the handover procedure of hierarchical mobile IPV6 of the mobile node, reduce the signaling interaction in handover process, and shorten handover delay.