Poly(ether imide) (PEI)-poly(dimethylsioxane) (PDMS) composite membranes and their modules were prepared,which are capable of selective CO₂ separation from the mixture gas. The gas flow rate, concentration, recovery ratioof H₂and removal ratio of CO₂ outflowing by stage-cut were characterized at 25°C and the constant pressure. In addition,to increase the recovery ratio of H₂, one stage, two stage series connection, and three stages series + parallel connectiontests were carried out. When the stage-cut was 0.32 for the three stages connection operation, the concentration H₂ of theproduced gas and the recovery ratio of H₂ was 97% and 85%, respectively. And also the removal ratio of CO₂ was 90%was obtained and the recycled gas concentration was similar with that of the feed gases.