: In this research, gas separation properties of polyvinyl amine –polyimide membranes and also effect of silica nanoparticles on the gas permeation properties of polyimide-polyvinyl amine has been investigated. Polyvinyl amine was synthesized trough hafman reaction. PI-PVAm membranes were prepared by thermal phase inversion method. Physical properties of synthesized polyvinyl amine and polyimide-polyvinyl amine membranes were investigated by FT-IR and SEM. Results obtained by FT-IR indicates that there is an interaction between polyimide carbonyl groups and amine functional group in polyvinyl amine. SEM micrographs confirm that interaction between polyimide and polyvinyl amine is strong and polyvinyl amine penetrated into the bulk of the polymer. The permeability of nitrogen, oxygen, methane and carbon dioxide were determined using constant volume method at the different pressure and temperature. The results of gas permeation experiments represented that by increasing the polyvinyl amine content in polymeric membrane,permeabilityof the non-polar gasesdecreased and co 2 permeability and selectivity increased. It has been observed that the selectivity of CO 2 gas over N 2 and CH 4 in polyurethane considerably increased.Permeability of CO 2 was increased from 5.2 barrer in pure polyimide to13.9 barrer in the membrane containing 10wt% of the polyvinyl amine. Furthermore.the selectivity of CO 2 /N 2 in the corresponding membranes demonstrated an increase from 21 to 278 in the polyimide-polyvinyl amine membranes. The gas separation performances of the prepared polymers have been comprised to Robeson upper bound. As shown the polyimide – polyvinyl amine membranes have high performance in separation of CO 2 . Polyimide-polyvinyl amine silica Nano composite membranes were prepared by thermal phase inversion method. The prepared membranes were characterized using SEM. The obtained SEM micrographs confirmed that the silica nanoparticles increased distribution of polyvinyl amine in polymer matrix. Gas permeation properties of polyimide-polyvinyl amine silica Nano composite membranes with silica content of 1, 5 and 3 wt.% was studied for pure gases at different pressure. The obtained results indicated the increment in permeability of all non-polar gases, and reduction in co2 permeability and also CO 2 /N 2 , CO 2 /CH 4 and O 2 /N 2 selectivity by increasing the content of silica nanoparticles in polyimide-polyvinyl amine silica membranes. Increment in non-polar gas permeability is due to interaction between silica particles and polyvinyl amine. Keywords: Membrane; Polyimide; polyvinyl amine; Silica; Nano composite; Gas permeation; Structure property;