Abstract: In order to optimize the performance of cooperative communication systems, a dynamic multi-relay decoded forwarding (DF) nodes selection algorithm MRS-DF is proposed. The algorithm jointly considers the residual energy information of nodes and channel state information (CSI) to optimize the network lifetime, to obtain longer network lifetime and greater channel capacity. Simulation results show that, for dynamic relay power distribution, the best performance can be reached by selecting 4 relays. The network lifetime and system channel capacity of MRS-DF algorithm are much larger than those only considering the channel state information nodes selection algorithm. In 10 simulations, the proposed algorithm can extend the network lifetime average of 201.1% and increase the channel capacity average of 164.55%.