The chipless cutting saw of the vacuum sizing production line is composed of a frame, a moving body, a rotary assembly, a clamping mechanism, a cutting tool device, and a PLC electric control system. During cutting, after the product is clamped by the clamping mechanism, the moving body moves backward on the rack rail under the action of traction. On the rotary assembly, the cutting blade is cut by the hydraulic feed system while cutting while revolving. And through the control of the limit switch to complete the cutting of a working cycle. The electrical control system is controlled by a separate human-machine interface PLC programmable system. The entire operation process is automatically completed, which not only saves manpower and material resources, but also greatly improves production efficiency.