Seamless steel pipe is mainly made from the process of stretch reducing, the tension reduction process is a continuous rolling process of hollow metal without mandril. The process of tension reduction is a continuous rolling process of hollow tubing without mandril. Under the condition of ensuring the welding quality of tubing, the welding tubing tension reduction process is to heat the tubing to more than 950 degrees Centigrade, and then the stretch reducing track machine is rolled into various finished tubing of external diameter and thick wall. In addition, the size accuracy of the steel pipe(especially the roundness and thickness of the tube) is better than that of the same type of seamless pipe by multiple stages of stretch reducing and automatic.