A method of cooperative relay selection based on network coding security is proposed for relay selection problem of cooperative communication system security in networked multi-relay scenarios, which is different from the existing relay node selection method. The algorithm not only merged with timestamp and homomorphic signature to construct the node degree of safety to find reliable relay, at the same time to considers the received signal to noise ratio at all relay nodes value and the channel gain to the source node. The simulation results show that the proposed method can improve the achievable rate of the destination node and reduce the outage probability on the basis of guaranteeing the safety of the relay node.