All steel parts are subjected to primary treatment such as shot blasting and sanding, and then the final surface treatment is completed by electrostatic epoxy-based powder spraying on the automatic spraying line. The coating thickness is 80um to 120um. There are the advantages of acid and alkali resistance, humidity and heat resistance, anti-aging, beautiful appearance, etc. and the product coating formula does not contain toxic elements, so as to avoid damage to the health of users.