For a new gas well， it is an important work to test the pressure drawdown curve of the bottom-hole flowing pressure under the condition of stable gas well production. The pressure drawdown curves of gas wells can be divided into the unsteady state stage， transition stage， and pseudosteady state stage. The unsteady state stage is also called the elastic one phase， and the pseudosteady state stage is called the elastic two phase. The former test data can be used to determine the effective permeability of gas reservoirs and the skin coefficient of gas wells； the latter test data are mainly used to evaluate the original gas in place controlled by a gas well. However， for tight and low permeability gas reservoirs， the production of a gas well after fracturing cannot remain stable and is decreasing. The elastic two phase method relationships of the pseudosteady stage of the pressure drawdown curves with a variable production which are expressed by pressure and pressure-squared respectively are proposed in this paper，and they can be used to evaluate the original gas in place of the volumetric gas reservoir. The practical application shows that these two methods are practical and effective， and the evaluation results are basically the same.