To reveal the factors responsible for generation of the nano-vibration of aerostatic bearings, computational fluid dynamics and three-dimensional numerical large eddy simulations were employed herein for the analysis of the air film flow field from the perspective of the microscopic flow field. First, five simulated experimental groups were designed to investigate the effect of the internal gas volume on the microscopic flow field using different single variables and under different relative gas capacities. Subsequently, the simulation results of different structure parameters were analyzed, according to which the excitation sources that can result in generation of nano-vibrations were determined. Finally, the influence of internal pressure on the flow field was illustrated via the simulation of different supply pressures. A certain internal gas volume leads to the nano-vibration of aerostatic bearings when the relative gas capacity is approximately 1%. The pressure fluctuation near the equalizing cavity may be the excitation source responsible for inducing nano-vibration; the internal pressure also influences the amplitude of the vibration to a certain extent. In conclusion, the changes in the microscopic flow field directly in fluence nano-vibration, while the vortex generated uponflow field transition is the major factor causing it.