Aiming at the spraying problem of complex curved surfaces with large curvature changes,an autonomous spraying attitude planning method based on particle swarms was proposed.The method was based on the workpiece point cloud model.The workpiece with large curvature changes was divided into several simple curved surfaces through an improved region growth algorithm,then each simple curved surface was down sampled by the spray gun bounding box according to the spraying process characteristics,finally the spraying attitude objective function was established.The spraying attitude of each surface of the workpiece was solved by the particle swarm algorithm.Experimental results with average curvature range of ［2.01×10-6,1.83×10-2］ show that the method can be used to effectively simplify the complex surface spraying problem,the surface with large curvature changes is divided into simple surfaces with regular boundaries,and the problem of the surface to be sprayed beyond the working space or the robot enters a singular state can be avoided.The method can autonomously realize the spraying attitude planning of complex curved surfaces.