Abstract: In view of problem that underground video monitoring system based on wireless Mesh network uses multi-hop transmission technique which leads to system capacity and signal bandwidth reducing, the paper proposed to use multi-input multi-output technology in wireless Mesh network to improve system capacity, and analyzed capacity of multi-input multi-output system and did simulation verification. Matlab simulation results show that the multi-input multi-output technology can effectively improve system capacity without increasing the bandwidth, and solve the problem of bandwidth reducing during multi-hop transmission of underground video, so as to improve real-time transmission quality of underground video.