One, the product quality of low cost PPGI prepainted galvanized steel coil is decided not only by the basic property of base material and coating, still depend on production craft and operation control technology. The operation control technology has a great influence on the physical properties and surface quality of the PPGI corrugated roofing sheet products. The production control technology analysis from the production process should focus on cleaning treatment, chemical coating treatment, coating (including initial coating, fine coating), curing 4 links. Two, PPGI prepainted galvanized steel coil production using two coating two drying production process. In order to ensure the coating quality of PPGI corrugated roofing products, it is necessary to remove oil, dust, rust and other pre-treatment work on the surface of the substrate before coating, which is the first step to ensure the coating process, but also to ensure the quality of PPGI corrugated roofing sheet products. Caitu processing purpose is to remove adhered on the surface of the base material of anti-rust oil, rusty spot, dust, etc, on the surface of the base material that cleaning chemical coating processing, form and Cr3, Cr6, + + as the basic skeleton network of chemical conversion coating, in order to increase the adhesion between substrate and coating, the durability of the base material of corrosion and coating. Three, the quality of the work determines the quality of the coating, and directly affect the coating flexibility, impact resistance, and other physical indicators. Determines the PPGI prepainted galvanized steel coil, PPGI steel sheet product coating adhesion. The purpose of initial coating, fine coating and curing is to apply the coating to the surface of the substrate and use the heating method to make the organic solvent volatilize the coating, making the organic coating closely combine with the substrate.