The food bag extrusion compounding and extrusion coating process is suitable for the compounding of various substrates. According to the requirements of product packaging, the food bag extrusion compounding and extrusion coating process is designed as required. 1. The production speed is fast, and it is suitable for mass production. The average composite linear speed is about 150 m/min, and the high-speed composite can reach 200-300 m/min. The composite speed of LDPE with high melt flow rate adopted abroad can reach 600 m/min. 2. The selection of base materials is extensive. Although the adaptive surface of the substrate is narrower than that of dry lamination, it is much wider than that of co extrusion lamination. 3. Good environmental protection. The extrusion coating composite requires the use of organic soluble extrusion type two-component polyurethane. 4. Low cost and good economy. 5. Extrusion lamination is the same as dry lamination, and inner printing and outer printing can be used. 6. The film thickness can be adjusted and controlled as required. Compared with coextrusion composite, the thickness of each layer of composite film can be controlled. Compared with coextrusion composite, the thickness of each layer of the composite film can be adjusted without confusion between layers, and the interface is clear. However, the thickness of coextrusion composite cannot be accurately adjusted.