The machine for retrieving the used plastic film after harvesting is an important tool for mechanization of retrieving the used plastics. In this paper,the main components parts for retrieving the used plastics were investigated. The equations revealing the relationship between the linear velocity of the pickup teeth and the ground speed of the machine were derived. The theoretical basis for designing this type of machine was provided. The trial and calculation proved that the designing principle for all components parts is right and the calculation results meet the demands for picking up the used plastic film.