Abstract: The operation performance of a membrane absorption-regeneration circulatory setup were investigated with a complex aqueous absorbent of N-methyldiethanolamine (MDEA) + piperazine (PZ) for CO₂ capture. Effects of gas and liquid flow rates, absorbent concentrations and regeneration voltages on CO₂ capture efficiency and mass transfer flux were studied. An optimal operation condition was determined by orthogonal optimization design. The results showed that, effects of gas flow rates on the capture efficiency was remarkably larger than that of liquid flow rates. The effects of the increase of the gas flow rates on the mass transfer flux was inconspicuous. The mass transfer fluxes rapidly increaseed with the increase of the absorbent concentrations. However, the flux no longer increased as the absorbent concentration reached a certain value. The optimum operation condition obtained through the orthogonal optimization design was the liquid flow rate in 110mL/min, the gas flowrate in 0.65L/min, absorbent concentration in 2.5mol/L and regeneration voltage in 210V. Here, the capture efficiency was higher than 95% and the mass transfer flux kept in 5.86×10^-4mol/(m²·s).