Abstract: Choke flow rate is often needed to be calculated during oil and gas field production and the volumetric adiabatic exponent used as a constant in the calculation is often assumed to be 1.3. In fact, the volumetric adiabatic exponent as a function of temperature and pressure should be used for choke flow rate calculation, and the exponent can be considered as a constant only under the conditions of low pressure. Based on the analysis of the impact of temperature and pressure on the exponent, it is concluded that the volumetric adiabatic exponent can be considered as a constant when the inlet pressure is lower than 10 MPa. When the inlet pressure is more than 10 MPa and outlet to inlet pressure ratio is less than 0.9, there is a big difference between the specific heat ratio and the volumetric adiabatic exponent, so the specific ratio can’t substitute the exponent. Under the same pressure and temperature, dry gas flow rate is larger than condensate gas flow rate from chokes of same size. The higher the condensate content is, the lower the gas flow rate will be