Recently QoS guaranteed real-time data support with user mobility in wireless Internet becomes more significant due to drastic increase of network users called netizens. Mobile IP(MIP) supporting user mobility evolves from versions v4 to v6 with comprehensive analysis of mobile users. However, Mobile IPv6 still has the buffering problem and problems occurred by the zigzag effect. In this paper, we propose a new MIPv6 handoff mechanism called partial dual unicasting(PDU) based on QoS supported RSVP signaling protocol. This scheme reduces the handoff failure rate up to about 24% and guarantees the time for the handoff completion. Furthermore, it resolves the ineffectiveness of path usage in dual unicasting(DU).