The cylinder bottom die forgings are mostly formed by the open die forging of the insert die on the hammer. The cylinder bottom larger than - 320mm is cast. Wuxi Tianrun die forging production equipment can produce the load capacity of 5t die forging hammer. The casting strength is low, and the cylinder bottom die forgings are used. After repeated analysis and research on the open die forging and closed die forging, the closed die forging process is adopted, which successfully solves the problem of forging large cylinder bottom with small tonnage equipment