This article introduces the analysis and treatment process of a commercial vehicle company receiving feedback from market customers that the paint film peels off the metal bumper of the exterior trim of the body during use.In response to the market feedback of faulty parts,through the confirmation of the customer's work site,at the same time,macro and micro failure analysis and material composition analysis were carried out.the cause of the fault was clarified and suggestions for improvement were put forward.It provides a favorable guarantee for the manufacturing quality of the product and provides reference for the upgrading and improvement of the subsequent process.