Abstract: In view of the problems of the existing data transmission system in coal mine underground, such as limited data transmission distance, inconvenient node deployment, limited sensor address and delayed data transmission, a data transmission system in coal mine underground based on 6LowPAN was designed. The system adopts combination with Ethernet and 6LowPAN protocol, and SPI, RS485 and other interfaces are reserved in data acquisition nodes to realize sensor data acquisition. Data acquisition nodes are wireless network nodes and can effectively select appropriate routing paths through the routing system to send sensor data to the data sink nodes. Wired connections can be built between the sink nodes and the boundary routes, and data can be uploaded to the ground server via Ethernet to achieve stable and reliable data transmission. The test results show that the system is obviously superior to the traditional data transmission system in terms of transmission delay, packet loss rate and throughput, and can efficiently and reliably transmit underground data of coal mine with good real-time performance, high communication rate and stability.