The　paper　studies　the　characterization　and　evaluation　technology　of　rotation　accuracy　of　hydrostatic　spindle　under　the　influence　of　unbalance.　The　dynamic　model　of　the　motion　error　of　the　hydrostatic　spindle　is　established　based　on　the　dynamic　parameters.　The　variation　law　of　motion　error　of　spindle　rotor　is　analyzed　under　the　unbalanced　mass.　The　paper　finds　that　with　the　increase　of　the　spindle　speed,　the　amplitude　of　the　spindle　error　motion　will　increase,　and　the　inclination　angle　theta　error　is　more　sensitive　to　the　change　in　the　rotational　speed.　In　the　total　synthesis　accuracy,　the　proportion　of　synchronization　error　decreases　with　the　increase　of　the　rotational　speed.　Finally,　the　least　squares　evaluation　algorithm　is　used　to　evaluate　the　rotation　error　of　the　hydrostatic　spindle,　and　a　method　for　evaluating　the　rotation　accuracy　of　the　hydrostatic　spindle　with　high　calculation　accuracy　and　calculation　efficiency　is　proposed.