A technology for manufacturing the stainless steel pipe used as the tail gas pipe of car includes examining raw material, shearing, welding to become pipe, drawing, pressure test, washing, annealing, straightening, sizing, cutting off, straightening, reducing diameter, sizing, cutting off, washing and refining. Its automatic cutter is composed of machine frame, base plate, fixature, small bearing holder and pressing plate, intermediate bearing holder, rotary plate, abrasive dis, and its mainshaft, motor, sizing unit, etc. The finished pipe features high size precision, smooth surface, and hith uniformity in hardness.