Abstract: At present, cooperative communication has become a key technology to achieve diversity gain. Terminal node with single antenna transmits data by coordinating each other, which can achieve spatial diversity and improve the whole performance of system. Meanwhile, cooperative node selection is very important in the study of collaborative communications. However, allocation and selection of a good cooperative node considering the optimal network performance is still an open problem in a fully distributed wireless network with multi-channel. In this paper, we proposed a cooperative MAC protocol based on cooperative increment value (CIV) and multi-channel (named as CIV-MAC). In CIV-MAC, alternative cooperative nodes are able to sense multiple channel control frames to obtain the channel state information (CSI) and calculate its CIV. According to the nodes’ CIV, the protocol would implement cooperative node assignment and selection. And then, it chooses the optimal cooperative node. At the same time, the system energy consumption will be reduced by use of the minimum power control. Finally, the simulation results with two different scenarios show that CIV-MAC can greatly improve the system performance compared with RBAR and CRBAR protocol in terms of energy efficiency and throughput performance.