In view of the complex and varied appearance characteristics of modern industrial products, the variation of the curvature of the surface boundary during painting will cause a large difference in the coating thickness. Based on the existing methods for planning the spraying trajectory on the surface of industrial products, a trajectory planning method suitable for the boundary curvature of the workpiece was proposed. Firstly, according to the plane static spraying model, the coating uniformity was taken as the optimized goal to solve the optimized path parameters, spray gun speed v, and the variation range of spraying distance［δmin ,δmax］. On this basis, the spraying path of the workpiece to be painted was generated. Finally, the validity and correctness of the proposed method were verified by simulation.