Abstract: The paper describes the development of the on-line retained-mandrel lubricating system of the Accu-Roll pipe mill line located at the Lubao Steel Tube Plant, Baoshan I & S Co. In accordance with the operation features the shielding type fast-spray system is capable of spraying the lubricant quickly without any clogging, well meeting relevant process requirements of the Accu-Roll mill plant. The said spray system has been patented via the Chinese Patent Bureau, being worth spreading.