The polysulfone mixed matrix membranes (MMM) with concentrations of graphene oxide (0.0, 0.25 and 0.5 wt.% of polymer) fabricated by a phase separation method.the obtained results show that the kinetic selectivity means the ratio of the penetration coefficients of two gases, which expresses the different sizes of the two gases CO2/N2 and CO2/CH4. first, by adding 0.25 percent by weight of graphene oxide to the composite matrix, the selectivity of CO2/N2 became 12.24 and 50 percent by weight of graphene oxide was 17.79. while CO2/CH4 selectivity was 10.94 and 14.14 respectively. For this purpose, by addition of graphene oxide to the membrane structure, Tg increased considerably due to the strong bond between polysulfone and graphene oxide. These strong bonds are due to the active agent groups present in the surface of graphene oxide, which have established a good bond with the polymer.