Based on the molecular motion and collision law of the gas in the aerostatic guide way of inflatable support area, the stratification theory of the gas film was proposed.The gas in inflatable support area was divided into near wall layer, thin layer, continuous flow layer, basis was proposed for dividing the thin layer and continuous flow layer, and the physical model and the corresponding equation were established.Gas flow patterns were simulated in gas film support area and calculated the pressure by LAMMPS.The result shows that with increasing air velocity, the effective pressure of gas film is decreased, continuous flow layer thickness is increased, and the thickness of the thin layer is decreased, there is no layered pressure in the gas film, when certain velocity is reached,and the velocity slippage can be ignored,which then verified the reasonableness of the stratification theory.