In order to research the effect of the lubrication medium on the gas bearing performance,the numerical calculation of the gas bearings which using air,carbon dioxide,hydrogen and helium as the lubrication medium was conducted through FLUENT.The variation of the load capacity of the aerostatic bearing with gas supply pressure and the variation of the load capacity of the aerodynamic bearing with rotation speed were analyzed.The trend of the carbon dioxide lubricated aerodynamic bearing load capacity under different ambient pressure and temperature was researched.The numerical results indicate that the lubrication medium has obvious influence on the load capacity characteristics of aerostatic and aerodynamic gas bearings.The order of bearing capacity of aerostatic bearing with different lubrication media is air,helium,hydrogen and carbon dioxide.The trend of the aerodynamic bearing load capacity with different lubrication media is basically consistent with the viscosity of the corresponding lubrication media.The influence of ambient temperature and pressure on the load capacity of carbon dioxide lubricated aerodynamic journal bearing is mainly reflected by viscosity of lubrication media,the load capacity of carbon dioxide lubricated aerodynamic thrust bearing increases approximately linearly with the ambient pressure.