A systematic method that integrates process simulation, capture cost estimation, and exergy analysis is applied to evaluate a gas separation membrane process for post-combustion carbon capture in a coal power plant. The influences of membrane performance and process configuration on the energy consumption, required membrane area, and capture cost have been studied. The results indicate that the energy consumption decreases with the increase of CO2/N2 selectivity, but a larger membrane area is required, while for a high CO2 permeance, the membrane area can be significantly reduced. The carbon capture ratio influences the specific energy consumption as well, which should be a trade off. For a two-stage membrane process, the capture load distribution between the first and second stage affects the separation performance greatly, and the optimal range varies with the other parameters. Under the assumptions in this work, the profiles of capture cost related to membrane parameters show that the optimal CO 2/N2 selectivity is 70-90. The exergy analysis indicates that the main energy bottleneck of a membrane technology is located in the membrane unit operation, which has relatively low exergy efficiency. On the other hand, CO2 compression has less potential for energy savings because it has already had very high exergy efficiency.