The invention discloses a material cutting device for a PVC injection molding machine nozzle. The device comprises a mold plate and the nozzle; a support is included, a swing air cylinder is arranged on the support, an air cylinder rod of the swing air cylinder is connected with a cutter connecting plate, a cutter is arranged on the cutter connecting plate, a through hole is formed in the middle of the cutter connecting plate, a limiting air cylinder is further arranged on the support, the cutter connecting plate is at least provided with one position to enable an air cylinder rod of the limiting air cylinder to stretch into the through hole so as to fix the cutter connecting plate, and a travel switch used for controlling the swing air cylinder and the limiting air cylinder is arranged on the nozzle; and due to adoption of the structure, when the nozzle retracts, the travel switch is triggered, at the moment, the limiting air cylinder retracts, the cutter on the material cutting device rotates downwards to cut the opening portion of the nozzle, and therefore the injection molding quality of a product and the cleanliness of a mold are improved.