For improving the coating body quality and the qualified rate of one painting inspection,the definition of shrinkage cavity and the factors that may affect the shrinkage cavity during the coating process and how to control it were introduced.With the help of theoretical analysis and experimental research,the process of pretreatment electrophoresis,gluing,grinding,mid-surface coating,drying and forced cooling and the relations among the on-site working environment and the shrinkage cavity and revealed the process control involving potential factors in shrinkage cavity were discussed.The results indicate that the formation of shrinkage cavity relates to many factors and on-site environment cleanness,staff operation,cleaning and maintenance of high clean area and the admission control of raw materials into factory make a great impact on the top coating shrinkage cavity.