Abstract: To solve the problem of automatic welding of intersection lines of large-scale offshore wind turbine jacket structures, a set of intelligent welding system for large-scale intersection line was designed. Through methods such as reachability simulation analysis, 3D scanning of welding trajectory and groove information recognition, theoretical calculation and simulation of intersection line welding trajectory and welding torch posture, the robot was guided to complete the intelligent welding of the intersection line. The welding stability of the robot welding is better, and the variation range of welding current and welding speed is small, resulting in better stability of heat input. The microstructure, hardness, impact absorbing energy and other mechanical properties of the robot welding joint were compared with those of the manual welding joint. The results show that the microstructure of the robot welding joint is more uniform and finer, and the hardness change of each region is smaller, and the impact absorbing energy is better.