Abstract: The mobility of the cooperative relay will greatly affect the performance of a cooperative system. Selection and handoff scheme of mobile relay is of great importance in distributed cooperation wireless networks. The paper proposes a mobile relay selection scheme under amplify-and-forward mode based on average channel gain to minimize the outage probability. For a single relay scenarios the handoff scheme is given. For other situations(multiple relay) the relay selection scheme is used to eliminate and add relays automatically so as to maintain the reliability of the cooperative mobile relay system. Simulation results show that the proposed relay handoff and selection scheme effectively reduces the outage probability, increases the diversity gain and system capacity to achieve the integrity of the well organized system.