Seeking an energy efficient and environmentally friendly technology for CO2 capture could be promising for reduction of CO2 emissions. Membranes have already been commercially used for selected gas sepa- rations and have potential to be used for CO2 capture. However, process and economic feasibility of mem- brane separation system significantly depends on not only membrane materials but also process operating conditions. Thus, membrane system design by process simulation was conducted in this work. A single stage membrane unit was designed to accomplish specific separation requirements of >80% CO2 capture ratio at a maximum acceptable membrane area 600,000 m2. The obtained characteristic diagrams showed that a minimum membrane performance of CO2 permeance 2 m3 (STP)/(m2 h bar) and CO2/N2 selectivity 135 should be achieved at a stage-cut of 15.2% and a feed and permeate pressure of 2.5 bar and 250 mbar, respectively. A two-stage membrane system using high performance fixed-site-carrier membranes by integration of compression heat was designed to achieve >80% CO2 capture ratio and >95% CO2 purity from a 18,260 kmol/h flue gas in a refinery. The simulation results showed nice potential for CO2 capture with a specific energy consumption of 1.02 GJ/ton CO2 and a capture cost of 47.87 $/ton CO2 captured.