Abstract: Described here in the article is the technical innovation of the lubrication system of the imported weld pipe mechanical expanding mill located at Julong Steel Tube Co., Ltd., involving modifications of such elements as the oil filter, the pneumatic reversing valve and the hydraulic pump, etc. Thanks to the said innovation, the oil filtration accuracy of the lubrication system has been significantly enhanced, accordingly the failure rate of the system is reduced, the service lives of the hydraulic components increased, and normal operation of the mill ensured. Moreover, the operation cost of the mill is considerably cut down due to the home-made wear parts used by the lubrication system.