The invention discloses a belt cutting device. The belt cutting device comprises a device body; a first supporting frame is arranged on one side of the device body; a first conveying roll is arrangedat the bottom end of the device body; a driven rod is arranged on one side of the first conveying roll; a fixing rod is arranged at the top end of the first conveying roll; a plurality of cutting fixing racks are arranged on the surface of the fixing rod; fixing screw holes are formed in the surfaces of the cutting fixing racks; cutters are arranged at the top ends of the cutting fixing racks; a first auxiliary rod is arranged at the top end of the fixing rod; and a second conveying roll is arranged at the top end of the first auxiliary rod. Through arrangement of the first auxiliary rod, a second auxiliary rod and a plurality of fixing holes, the tension of the cutters during cutting is increased, the cutting precision is improved, the cutting speed is increased, and the cutting efficiency is improved accordingly. The belt cutting device is reasonable in design, simple in structure, safe, reliable, convenient to use and high in practicability and has great application and popularization value.