The work aims to solve the problem that the defective carton-missing products packaged in cases cannot be effectively detected and eliminated in the production process of YP13 case filling and sealing machine. A new visual inspection system of YP13 case filling and sealing machine was designed. By studying the key technology and integrated with the installation of industrial camera and trigger pulse signals, designing the mounting bracket, capturing the dynamic image and designing the PLC control program, etc., the efficient detection and accurate elimination of defective carton-missing products packaged in cases were achieved. After the visual inspection system was put into use, the detection and rejection rate of such defective products was greater than or equal to 99.9%, and the false detection rate was less than or equal to 0.02%. As the visual inspection system can improve product quality and reduce material consumption, it can be popularized in all the case filling and sealing machines of 2×25 bars or 25 bars in the industry.