Abstract: Described here in the essay is the REM(rotary expand mill),involving such aspects as the rolling principle of the REM,and the technological requirements and equipment for the mini-flow REM.It is regarded via relevant analysis that the inner surface quality of the steel pipe as produced by the REM can be greatly improved,and the depth of the inner spiral defect thereof also reduced by means of optimizing the plug parameters;the rolling jamming trouble as caused by rather low temperature can be significantly improved by means of setting up in addition a reheating furnace between the REM and the reeling mill;and the quality of the steel pipe as made with the mini-flow REM is not only satisfactory to the application requirements,but also features cost effectiveness.The process is practical.