In　view　of　lack　of　analysis　and　optimization　of　existing　hydrostatic　spindle　motion　errors,　a　dynamic　model　of　the　spindle　motion　error　is　constructed　based　on　structural　parameters,　and　the　laws　of　dynamic　parameters　of　the　spindle　rotor　at　different　rotational　speeds　with　an　unbalanced　mass　are　quantitatively　analyzed.　The　mathematical　model　of　the　spindle　motion　error　is　taken　as　the　objective　function,　and　the　spindle　system　parameters　are　used　as　design　variables.　Genetic　algorithm　is　adopted　to　optimize　the　motion　error　of　the　hydrostatic　spindle　system.　In　the　single-factor　optimization　analysis,　the　optimization　efficiency　for　the　radial　error　motions　x　and　y　of　the　spindle　system　and　the　spindle　inclination　angle　θ　reaches　41.22%,　25.21%　and　66.16%,　respectively,　and　the　efficiency　gets　4.7%　during　multi-objective　optimization.　The　optimized　spindle　motion　accuracy　is　significantly　improved,　and　a　combination　of　structural　parameters　is　obtained　to　heighten　the　hydraulic　static　pressure　spindle　motion　accuracy.　©　2020,　Editorial　Office　of　Journal　of　Xi＇an　Jiaotong　University.　All　right　reserved.