The invention discloses a novel cutting device of a plastic film winding machine and relates to the technical field of plastic film devices. The novel cutting device comprises a cutting roll shaft, acutting tool, a winding shaft, lifting devices, sliding grooves, a slide rail, a support and limiting blocks. The winding shaft for winding a plastic film is mounted at the front end of the support. The limiting blocks are fixed to the upper portions of the two sides of the support. The slide rail is fixedly arranged between the limiting blocks. The cutting tool is arranged on the slide rail and can slide left and right. The height of the upper end of the slide rail is not less than the height of the top of the winding shaft. The cutting roll shaft is arranged below the slide rail. The cuttingroll shaft is connected with the lifting devices arranged below the cutting roll shaft. The two ends of the cutting roll shaft are arranged on the sliding grooves formed in the inner walls of the twosides of the support in an up-down sliding mode. The novel cutting device is convenient to operate, good in cutting effect, high in practicality and easy to use and popularize, and the plastic film winding efficiency is effectively improved.