Abstract: The deformation process of the Ф159 mm MPM plant as located at a certain domestic company is analyzed. After it failed to be continuously used，the Ф172 mm series mandrel can just once re-turned to be the Ф112 mm series mandrel，which brings about disadvantages like large turning quantity and low utilization of the mandrel.Addressing this problem，the 152 mm intermediate pass series is proposed to be added. As a result，the product size range is expanded，and the occupation rate of the sizing mill stands is reduced，and the wall thickness accuracy improved. Meanwhile，gradient turning of the mandrel is realized，resulting in higher mandrel utilization and lower operation cost of the plant.