The effects of putty slag in the license plate hole of passenger car on the fixing bolts installation often cause customer complaints.Sometimes,this problem would induce the decrements of the product quality and sales.The formation origin of the putty slag in the license plate hole was analyzed.The welding quality and polishing quality of the license plate hole were improved by.optimizing welding,polishing and coating putty scraping.Finally,the putty scraping was canceled at most of the license plate holes,and a small number of license plate holes were treated with patchy putty avoiding the holes to make up for defects,the problem of putty slag in the license plate holes was completely solved.