Abstract: According to the requirements of robot welding motion simulation and multi-layer and multi-channel path planning, an open robot welding off-line programming system based on WebGL is developed. Firstly, a robot MAG welding system based on laser vision sensing is built, and then a simulation platform is built by using JavaScript, WebGL and other technologies. The three-dimensional point cloud data of weld bead is obtained through the sensor, and the point cloud processing technology is used to extract the weld bead feature information. On this basis, a multi-layer and multi pass path planning strategy for 20 mm thick V-groove steel plate is further proposed, Finally, the welding experiment of 4 layers and 10 passes of V-groove was completed. The results show that the system provides a reliable way to realize the key technologies of robot welding automation and intelligence.