The application of waterflooding characteristic curve in the calculation of dynamic reserves and recoverable reserves of water carrying gas reservoirs is controversial. The assumption of constant formation pressure in traditional waterflooding characteristic curve is inconsistent with the fact that formation pressure drops in water carrying gas reservoirs, and the relative permeability curve is not accurately fitted at low water saturation or high water saturation. In order to solve the above two problems, the gas-water phase permeability ratio and water saturation semi-log curve were fitted, and a new gas-water phase permeability characterization method was proposed, which improved the curve fitting accuracy. On this basis, a new waterflooding characteristic curve suitable for water carrying gas reservoirs was derived by taking into account the active degree of water body and the water invasion constant in combination with the gas-water two-phase seepage law and the principle of material balance. The equation can be automatically fitted by genetic algorithm to determine the water invasion constant and dynamic reserves. According to the fitting water invasion constant and dynamic reserves, combined with waste water gas ratio, the production water gas ratio prediction and recoverable reserves calibration can be realized. Based on the production data of 4 real water-producing gas wells in Sebei gas field, the accuracy of the new waterflooding characteristic curve was demonstrated. The results show that the new method is more accurate, and the correlation coefficient of the new waterflooding characteristic curve is greater than 0.85. The dynamic reserve error calculated by the new waterflooding characteristic curve and the material balance method is 3.52%, and the new waterflooding characteristic curve avoids the calculation error caused by the drop of pressure drop curve after water intrusion in the water carrying gas reservoir. It can be seen that the new waterflooding characteristic curve has certain guiding significance to the calculation of water carrying gas reservoir reserves and production prediction.