The work aims to analyze the causes for the defects in the inner packaging of multi-layer food package to reduce the defect rate of the inner packaging in the food production process. Taking GDXII packaging machine as an example, the causes of six typical defects of inner packaging aluminum foil paper, such as wrinkles, breakage, warping, exposed bottom, scratches and stitching errors, were analyzed, and the parameters of inner packaging clamping device, embossing device, cutting device, acceleration device and packaging molding device of GDXII packaging machine were adjusted respectively. The adjusted and optimized GDXII packaging machine was running stably during production, with the production volume of the inner packaging increased to 24,350 from 23,977 before optimization and adjustment, and the defect rate of the inner packaging aluminum foil paper decreased to 1.92% from 4.44% before adjustment. In actual production, similar food package manufacturers can determine the appropriate parameter adjustment scheme of packaging machine according to the optimization and adjustment ideas and methods, so as to reduce the loss rate of inner packaging defects in the production process, and improve the credibility of products and the economic benefits of enterprises.