Ensuring the safe, stable, and efficient operation of natural gas residual pressure power generation equipment necessitates a systematic examination of design parameters. These parameters include the inlet and outlet pressures and flow rates of natural gas, and the methodology for calculating generated power, taking into account the substantial fluctuations in natural gas flow rates. This research involves an analysis of historical data on natural gas transmission conditions to estimate the annual cumulative power generation for various design scenarios, accounting for fluctuations in natural gas flow rates. By adhering to the principle of maximizing annual power output and economic benefits, the optimal design parameters for natural gas residual pressure power generation equipment can be determined. Subsequently, the selection specifications for the equipment can be ascertained, enhancing the scientific validity and rationality of the design parameters and the power generation calculations. The method for calculating power generation, which accounts for fluctuations in natural gas flow rates, is applied in determining the design parameters and power generation capacity at a gas transmission stations. In this study, the calculation results are consistent with the actual performance of the equipment. The design parameters and power generation capacity of this equipment meet the actual operating conditions and can improve design and the accuracy of feasibility study.