The invention discloses a ring piece manufacturing process taking S48C as a material and adopting after-forging waste heat for quenching. The ring piece manufacturing process comprises the following process steps of blanking, heating before forging, forging blank-manufacturing, ring rolling, quenching through the after-forging waste heat and tempering. According to the ring piece manufacturing process, the after-forging waste heat is utilized to quench a ring, so that the after-forging waste heat is not wasted, and accordingly, the production cost can be lowered; the ring does not need to be reheated for quenching, thus the production time can further be greatly reduced, and the production efficiency can be improved; and in addition, in order to enable the ring quenched through the after-forging waste heat to have the good mechanical properties, process parameters are further improved and refined aiming at ring pieces of different sizes, the product properties are more stable and moreexcellent, and thus the ring piece manufacturing process is suitable for automatic mass production of the ring pieces.