The core of membrane separation is the physical process of gas separation based on the different diffusivity of different components in the air in the membrane fiber wall (polymer material). Polymer material is made into the thickness of the hollow fiber membrane as a human hair silk, the gas inside the hollow fibre membrane by the different components of the gas in the fibre wall seepage velocity is different, lead to different osmotic quantity, through a certain length of fiber membrane selective permeability, at the end of the film fiber get need purity nitrogen (90 ~ 99.99%), membrane fiber wall osmosis oxygen-enriched gas emissions and the concentration of oxygen enrichment can reach about 40%.