Multilayer types of thin film composite(TFC) membranes were prepared. Poly(dimethylsiloxane)and poly-4-methyl-1-pentene were used as a coating material and polysulfone was used for a porous support membrane. Permeation data of oxygen and nitrogen through TFC membranes at different pressure and thickness ratio of coating layer were obtained and the relationship between structure of membranes, permeability and selectivity were analyzed by applying resistance model. The values of permeability coefficient and ideal separation factor predicted by resistance model were well fitted with the experimental data. Oxygen was enriched up to 34.5% in the permeate stream under the condition that pressure difference and cut were 5kg/㎠ and 0.05 respectively. The ideal separation factor of this three-layer TFC membrane was 3.4 and the permeability of oxygen was 1.9X10^-5 [㎤(STP)/㎠.sec.cmHg].