Based on the background of automobile painting,the problem of ash particles in the four-door painting process of automobiles is studied,and corresponding improvement plans were proposed to address the causes of the problem.First of all,combined with the Pareto diagram,the paint chip problem of four doors of K-model painting(which belongs to a kind of ash particle problem)is determined to be the main factor affecting the high-frequency problem of the off-line car of this model.Secondly,the problem analysis steps and process of the 8D-method are outlined,and the enabling standard of the 8D-method was described in combination with the paint chip problem.Thirdly,through the fishbone diagram method and its terminal factor analysis,the structural defect of the existing four-door tooling of the K-model is determined to be the main cause of the paint chip problem.Finally,based on the research and implementation of the 8D method,the frequency of ash particle problems was reduced through the optimization of the four-door toling of the K-model,the rework cost caused by the ash particle problem was reduced,and the long-term problem of painting quality was effectively solved.