Abstract: Among the schemes of mobile IP and RSVP integration, common router's computation is the key to reduce RSVP path handoff delay and end-to-end cost. In this paper RSVP path handoff schemes in IP networks are studied, an adaptive common router selection algorithm(ACRS) is represented, which satisfies application's quality of service (QoS) requirement, and balance between RSVP path handoff delay and end-to-end cost is kept via control parameter λ. In ACRS, optimum common router (OCR) is selected by two steps. Firstly, the node in previous path, which is nearest to new arrived node, is selected as common router, if the nodes are more than one; the nearest node to correspondence host is selected as CR. The RSVP path through CR between new arrived node and correspondence host must satisfy application's QoS requirement. Secondly, the RSVP path through CR between new arrived node and correspondence host is inspected, if there exists an zigzag path, then CR is re-selected, otherwise the selected CR is OCR. Through the performance comparison with other RSVP path handoff schemes, the results of experiment show that ACRS can support fast and adaptive RSVP path handoff.