In view of the large range of complex welds and the poor welding conditions in the narrow space in the production of large weldments,a new type of mobile welding robot was designed.Three independently driven OMNI wheels were used as the mobile mechanism of the robot,and the supporting wheel and adjustable magnetic adsorption device were installed on the chassis of the mobile mechanism at the same time,and the 5-DOF manipulator was designed as the welding actuator.The kinematics analysis of the robot mobile platform and the manipulator and the whole kinematics analysis were carried out respectively,and the functional relationship between the end effector of the robot and the angular displacement of the drive wheel and the manipulator joint was deduced.Aiming at the problem that the weld path with large curvature changes is difficult to weld,a path planning method of mobile platform based on improved particle swarm optimization algorithm and multi-segment straight line approximation curve was proposed,and the path planning algorithm was verified by MATLAB simulation to complete the discretization of the weld with arbitrary curvature curve.So the number of discrete points of the weld is reduced,the efficiency of path planning of the moving platform is improved under the premise of satisfying the welding accuracy.