Abstract: The material of the large annular thin-walled forging is 30CrMnSiA steel, the maximum diameter is 1630mm, the height is 230mm, the wall thickness is about 25mm, the hardness after quenching and tempering is required to meet 33～38HRC, and the degree of warpage deformation shall not exceed 3.28mm. Forgings are tested by using special tooling, after 900℃ oil-cooled quenching and 500～520℃ tempering, the hardness value and deformation degree of multiple forgings are detected, and the hardness value is controlled in the range of 35～38HRC, and the deformation is controlled with in 3.28mm. It effectively solves the problem of insufficient hardness and excessive deformation in the process of quenching and tempering of the forging, and provides an technical support for the company’s production and manufacturing of this type of workpiece.