Abstract: In order to select the cooperative relay in amplify-and-forward rayleigh two-way relay channel, the distributed two-way relay selection scheme based on partial channel information was proposed. Scheme implement distributed two-way relay selection based on received SNR at two-way channel. The forwarding or not is determined threshold which satiated the target SNR requirement was derived. Each relay decides whether to participate in forwarding or not is determined according to the forwarding threshold. Furthermore, when the total transmit power was constrained, optimal power allocation strategy was proposed based on distributed relay selection. The strategy makes received SNR at two-way channel more approaching. Simulation results indicate that the transmission rate of the distributed relay selection scheme is nearly the same as the optimal multiple-relays selection scheme. The complexity of scheme is considerably reduced, especially when the number of relays increases. Optimal power allocation strategy can improve the energy efficiency and decrease the power almost 7% in the same performance.