In　order　to　improve　the　machining　precision　of　the　aerostatic　bearing,　an　eccentric　rotor　orbit　model　considering　the　microscale　effects　is　established.　A　flow　factor　Q　embodying　the　effects　in　the　microscale　is　introduced　into　the　fluid　control　equation,　the　dynamic　stiffness,　and　damping　coefficients　of　bearing　are　calculated　considering　the　microscale　effects.　According　to　the　actual　working　condition　of　the　shaft,　the　modal　analysis　in　both　cases　(with　and　without　the　microscale　effects)　is　performed.　And　with　the　modal　information,　the　dynamic　orbit　in　both　states　(with　and　without　the　microscale　effects)　is　described　by　the　deduced　orbit　model　of　the　shaft　system.　Finally,　experiments　of　the　frequency　by　LMS　vibration　test　system　and　shaft　orbit　by　displacement　sensor　are　measured,　and　the　results　indicate　that　the　simulated　results　considering　the　microscale　effects　are　more　similar　with　the　actual　experimental　one,　which　provides　a　guideline　and　evaluation　standard　for　further　optimization　design　and　precision　control　of　the　shaft　system.