Abstract: The defects of the steel tube as caused during hi-pressure water descaling process mainly include pitted surface and the surface secondary oxidization.Briefed here in the paper are the descaling-related elements responsible for the said defects and relevant preventative actions.Thanks to the optimization of both the design parameters of the descaling equipment and the technological parameters of the equipment units located before and after the decaling system（i.e.the reheating furnace and the sizing mill,etc.）in the tube production line,the tube descaling performance is considerably improved.