The choke valve, a main component of Christmas tree, is design to control production rate of the oil well, with working pressure up to 20000psi. Choke valves can be classified as follows: adjustable choke valves and positive choke valves. By rotating hand wheel to move the stem, the adjustable choke valve is designed to adjust the effective area available for the flow to accomplish control of production rate. The positive choke valve is design to accomplish control of production rate by changing flow beans.