Abstract: The W.T. accuracy status of the seamless steel tube is studied by means of observation of the bore shape,and measurement of the wall thickness. And the alloy microstructure is analyzed with the scanning electron microscope (SEM). The results show that the W.T. evenness of the seamless steel tube is improved by means of adjusting the tension coefficient of the stretch reducing process and rolling with the equi-wall or the reducing mode. The accuracy status of the W.T. of the seamless steel tube is studied via observing the bore shape of the pipe and measuring the W.T. of the pipe. And the alloy microstructure is analyzed with the scanning electron microscope(SEM). The results show that during the stretch reducing process,both the W.T. evenness and accuracy of the seamless steel tube can be improved by means of adopting big tension coefficient to match with rolling with the equi-wall or reducing mode. The alloy microstructure of the seamless steel tube as rolled with big tension coefficient features homogeneous distribution.