A numerical method is established to describe the distribution of pressure and temperature in the natural gas wellbone with downhole choke from wellhead to bottom. The Mach number in the outlet of the choke is calculated and used to discriminate the flow state. Then, according to the value of the Mach number, parameters in throat and inlet of the choke are also calculated. At last,based on the preceding numeration, pressure and temperature of upstream can be solved. The computed results of Bao No.1 wellbone show that values of pressure and temperature rapid drawdown in the outlet of the downhole choke, and then quickly rising after the section of shock wave.
