In order to improve the welding quality and efficiency, it is necessary to solve the problem of low efficiency and high difficulty in manual programming of multipath/multilayer welding.A robotic offline programming software was developed for multipass welding robot based on OpenCASCADE modeling engine.The welding seam information was extracted from the workpiece model instead of the online teaching operation.A path planning algorithm for userdefined weld bead number was proposed to determine the space position and the welding speed of each bead,the end attitude of welding torch was planed to avoid collision with the workpiece.Through the robot machining simulation movement, it is shown that the position of each weld bead is accurate and the attitude is 〖JP2〗smooth, which verifies the correctness and feasibility of the path planning, and good welding effect is obtained in the actual welding test.