The pinholes and shrinkage holes in electrophoretic coating are common defects in the process of substrate surface treatment,which seriously affect the anti-corrosion performance of products.The solution of large-area pinholes and shrinkage holes in the appearance of an electrophoretic coating film of a certain coating line were introduced.In the process,5M1E was used to describe the investigation,test and defect locking in detail,and corresponding solutions were formulated according to the test results.