Abstract:This paper introduced a portable tool to change high temperature and high pressure valve seat. Based on this tool, a new type turning tool, including butter, vertical guide liner, sleeve, fixing flange, hand wheel, lock hoop and other parts, was designed. To adjust position and depth of turning tool per valve seat depth and valve seat hole inner dimension, turning tool will drilling and move vertically to turning on site. This tool requires less operational still, less change term and will increase work efficiency.