This　paper　presents　the　influence　of　the　microscale　effect　on　the　radial　rotation　error　of　aerostatic　spindle,　which　is　determined　by　the　corresponding　stiffness,　damping,　and　unbalance　mass.　A　microscale　gas　film　flow　model　is　used　to　simulate　the　static　performance　of　the　aerostatic　bearing　by　introducing　the　microscale　effect　factor　Q　in　this　paper.　Firstly,　the　radial　stiffness　and　damping　coefficients　of　aerostatic　bearing　were　calculated　considering　microscale　effect　factor　Q,　therefore,　the　position　of　the　rotating　shaft　in　radial　plane　was　deduced,　and　the　corresponding　rotation　error　was　obtained.　Finally,　the　simulation　results　of　the　stiffness　and　radial　rotation　error　were　verified　by　the　experiment　on　the　shaft　test　table,　and　the　motion　orbit　was　measured　by　a　displace　sensor　with　a　high　precision　standard　ball.　The　experimental　results　indicated　that　the　simulated　result　considering　the　microscale　effect　factor　Q　was　more　consistent　with　the　actual　experimental　value,　which　provided　a　reference　for　the　design　and　optimization　of　the　aerostatic　spindle.