In the MPLS-based Mobile IPv6 network, when mobile node performs handover, it needs to rebuild label switching path, which impacts the handover delay and causes packets loss. Reused parts of the path overcome the above reasons, which propose a cross-router (CR) algorithm. It modifies the label information base (LIB), that is, increases two fields: the mobile node address and the time counter. When the mobile node performs handoff and registration, the message arrives a router every times, it will look up the modified LIB, whether the mobile node was registered or not to confirm the CR. The theoretical analysis shows that the performance of delay is the more obvious with the increase of the hops. The simulation result proves that the signaling traffic have been decreased 20%, when the mobile node performs register. This proposed achieves reused part of the path and improved network quality of service (QoS).