Relay selection scheme with multiple source-destination pairs and multiple potential relays in cooperative relay networks considering co-channel interference (CCI) is proposed in this paper. In cooperative relay networks, which relay nodes are selected has great impact on the system performance. It is an optimization problem for selecting suitable relay nodes. The exhaustive search can solve this problem but the complexity will increase factorially with the network size, i.e., the number of source-destination pairs and the number of relays in the network. This paper proposes a novel quantum particle swarm optimization (QPSO) based relay selection scheme which can maximize the system throughput of the cooperative relay networks but has less computational complexity. Simulation results show that QPSO based relay selection scheme has the ability to search global optimal solution compared with other relay selection schemes in the literature.