Abstract: In order to solve the problem of large amount of side film of agricultural film after the operation of 4 MKJ plastic film recovery machine, and to meet the requirements of baling success rate, optimize the hydraulic system of 4 MKJ plastic film recovery machine.The disc used to dig film is installed on both sides of the stem crushing device to improve the recovery rate of residual film. The height adjustment of the stem crushing device, the raking tooth film collecting device and the disc used to dig film, the opening and closing action of the film rolling plate and the film rolling belt are realized through five sets of oil cylinders symmetrically installed on both sides of the machine.By connecting the pilot relief valve and the direct acting relief valve in series in the oil inlet of the regulating cylinder of the baling device, the regulating cylinder of the baling device can flexibly compensate the expansion of the diameter of the film baling.Using AutoCAD 2020 software to draw the hydraulic system schematic diagram.The baling and residual film recovery tests were carried out in the field.The baling success rate and residual film picking rate of the 4 MKJ plastic film recycling recovery machine supporting the hydraulic system were statistically analyzed.The side film recovery effect was evaluated by comparing the residual film recovery rate when the disc used to dig film was installed with that when the disc used to dig film was not installed.According to GB/T 14290-2008, the baling success rate was selected as the index to evaluate the baling situation. Field experiment showed that the baling success rate was 96% and the residual film picking rate was 94.2%, which met the application requirements.The use of the disc used to dig film can effectively reduce the side film residual and improve the residual film picking rate.The hydraulic system of baling device of 4 MKJ plastic film recycling recovery machine can ensure the baling success rate of film baling.