In view of the defects such as black spots, scratches, holes etc. in the production process of PE heat shrink film affect the appearance of the film products and reduce the use performance of the film, a machine vision system is adopted to quickly and accurately on-line detect the defects in order. Production practice proves that it is the first time that the machine vision technology is applied to PE heat shrink film production line, which can automatically identify the product defects recorded in early warning, solve the fatigue missed detection of traditional manual detection, meet the requirements of high speed, high resolution and non-destructive detection in production, control and improve the surface quality of the film, and reduce the economic losses caused by bad quality goods returns.