Abstract: In order to understand gas reservoirs, find out the problems during gas field development and formulate the reasonable working system, the unit pressure drop method for gas production was proposed. Based on the principle of molar weight conservation, the material balance equations of the constant volume and abnormal pressure condensate gas reservoir were established, by which the expression of unit pressure drop for gas production was derived. The case study shows that the unit pressure drop for gas production appears increasing and then decreasing along with the pressure reducing, which is mainly related with propagation of pressure wave and deviation factor. By comparison of the actual curves with theoretical curve, we can determine if water invasion or other problems are happened. This method is simple in calculation and better in applicability