NOVELTY - A hybrid membrane comprises sulfonated polyether ether ketone and carboxylated silica microspheres in weight ratio of (0.80-0.95):(0.20-0.05), and has thickness of 55-80 mu m. The sulfonation degree of sulfonated polyether ether ketone is 45-75%.    USE - Hybrid membrane is used in separation of carbon dioxide/methane gas (claimed).    ADVANTAGE - The hybrid membrane is prepared by simple process, and has high selectivity and permeability with respect to carbon dioxide/methane gas.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) preparation of hybrid membrane. Methacrylic acid, styrene and 2, 2-azo-bis-isobutyrynitrile according to 15: (10 to 30): (10 to 30): substance amount of 1 to disperse in acetonitrile, mass fraction is 1 to 5% suspension. Sulfonated polyether ether ketone is added into N,N-dimethylacetamide solvent and stirred at room temperature, to obtain 5-15% sulfonated polyether ether ketone solution. Carboxylated silica microspheres are dispersed in N,N-dimethylacetamide solvent, mixed for 12-36 hours, 10% sulfonated polyether ether ketone solution is added, stirred for 24 hours and the resultant solution is maintained for 1-3 hours, to obtain sulfonated polyether ether ketone-carboxylated silica microspheres casting solution. The obtained casting solution is then poured into a glass petri dish, dried at 60 degrees C for 12 hours and then dried at 80 degrees C for 12 hours, to obtain hybrid membrane. The carboxylated silica microspheres are prepared by adding silica spheres having diameter of 100-800 nm in mixed solution of tetraethyl orthosilicate and 25 %mass aqueous ammonia in mass ratio of (0.5-10):1, adding anhydrous ethanol, stirring uniformly at room temperature for 24 hours, adding 3-(trimethoxysilyl)propyl 2-methyl-2-propenoate, stirring at room temperature for 24 hours, centrifuging the resultant solution, washing the resultant material with water three times and with ethanol once, and drying. The mass ratio of tetraethyl orthosilicate and 3-(trimethoxysilyl)propyl 2-methyl-2-propenoate is (1-20):1; and    (2) usage of hybrid membrane in separation of carbon dioxide/methane gas. The hybrid membrane has carbon dioxide/methane gas selectivity of 33-54 and permeability of 852-1421 barrer.