Abstract: Described here in the paper are the development of home-made parts to replace the original hydraulic components of the three major imported units(i.e.,the steel plate edging machine,the steel tube forming mill and the mechanical expanding mill) consisting of the SAW straight welded tube plant located at Julong Steel Tube Co.,Ltd. The operational practice shows that the substitution of the home-made parts for the original foreign-made parts not only produce no negative influence on the normal performances of the hydraulic systems,but also has brought about such advantages as reduction of the operation costs,cut-down of the spare part inventories,saving of hard currency,shortened purchase time and consistent normal running of the plant.