During the quenching or tempering process of motorcycle sprocket, the waste heat of product workpiece can be used to form a layer of reaction film on its surface, which is convenient to obtain better appearance and antirust performance. According to the new quenching oil, a kind of reaction film can be formed on the gear surface during the quenching process of the product workpiece, so as to improve the anti friction performance and surface state of the gear. The quenching oil is ordinary vg220 quenching oil and a new type of graded quenching oil. Phosphate compound additives are added to the ordinary vg220 basic quenching oil to form a protective film on the surface of the product workpiece. The quenching temperature is 120c. Adding phosphate compound to the quenching oil can generate a kind of compound on the surface of the workpiece. Therefore, according to the compound generated by quenching in this kind of oil, the anti-oxidation adhesion resistance, friction and wear resistance and fatigue pitting resistance of motorcycle sprocket can be improved. It is more suitable for products that do not need grinding after quenching and tempering.