Abstract: On the base of finite element simulation for one stand of 152.5BR passes system in stretchreducing mill, the distribution of equivalent plastic strain and tube wall thickness along the section is uneven. The position of maximum is located at the gap of roll. After changing the position at gap and root of roll and adding up, it results in polygonization of the wall thickness. Rolling tests for 152.5BR passes systems validate the result of finite element simulation.