Abstract: Briefed in the paper are the main aspects of the Φ140 mm floating mandrel mill located at Baoshan Iron & Steel Co., Ltd., including the manufacturing process flow, production efficiency and adjustment of the product category, etc.Also described here are some important technological innovations and development related to the mill operation line, involving"bulging"control for the floating mandrel mill proper, the CEC control and the polygonization groove of the stretch reducing mill, modification of the piercing mill, and W.T.eccentricity ratio control of the pierced shell, etc.The mill operation line is always maintained with excellent production performance owing to proper product category adjustment, technological innovation and long-term acuminated data package.Up to now, among the domestic mandrel mill plants engaged in producing pipes under Φ180 mm, the said Φ140 mm floating mandrel mill line still remains rather competitive.