Aerostatic lubricating is the key technology in the field of precision engineering. The mechanical characteristics of air film

such as pressure distributing

bearing capacity and stiffness is the main factor that determine the stability of air-bearing position. Simplified Reynolds equation is widely employed in aerostatic bearing design

which leads large static error. This paper does research work on mechanical characteristics of aerostatic bearing such as pressure distributing principle

bearing capacity. Going on the premise that jetting air from orifice has the attribute of air impingement jet

the paper introduces finite volume method of computational fluid dynamics (CFD)

applies control equation set k-ε model closed of isothermal air for mechanical characteristics numerical analysis of air film and unveils the pressure distributing principle of different thickness air film on aerostatic bearing working plane. The numerical analysis shows that the pressure distributing principle of air film from orifice to edge of air-bearing along the working plane is not degression mentioned by simplified Reynolds equation

but fluctuation that the air flow pressure sharply drops under the atmospheric pressure nearby orifices

then gradually increases above the atmospheric pressure and reverses finally. Based on the analysis of air film thickness and aerostatic -bearing bearing capacity

this paper points out that elastic self-excited vibration caused by gas-solid coupled between air film and aerostatic bearing is the main block of aerostatic bearing’s application in nano-positioning.