Abstract: In view of problems that underground wired transmission mode has difficulty in cable deployment and cables are extremely vulnerable, traditional wireless local area network has short communication distance and cannot adapt to the long and narrow environment of coal mine underground working face, a video monitoring system of mine working face based on wireless multi -hop network was designed.The system consists of video acquisition node,wireless multi -hop network (including gateway nodes, transmission nodes and network switches) and clients. The video acquisition node completes video information collection, encoding and packaging, and sends the collected video as data stream through the push streaming software MJPG -streamer; the wireless multi -hop network adopts optimal link state routing (OLSR) protocol for ad -hoc networking, so as to realize the connection between collection node and gateway node; the clients receive the video streams from various monitoring channels, and realize the functions of multi -channel video real -time display, remote monitoring, storage and playback. The actual test results show that after 3 -hop transmission, the system throughput is 10.1 Mbit/s, the packet loss rate is 2.2%, and the average delay jitter and system end -to -end transmission delay are better than traditional wireless LAN -based video transmission systems. Practical application results show that when the distance between nodes in the working face is within 70 m, the system operates well; the video monitoring system based on wireless multi -hop network and the video monitoring system based on wired transmission basically have the same image quality.