To　control　and　accurately　calculate　support　stiffness　and　critical　speed,　numerical　calculation　models　have　been　established,　which　considered　the　mixed　preload　mechanism　of　angular　contact　ball　bearing.　Taking　a　spindle　system　as　finite　element　model,　bearing　group　model　and　shaft　model　were　coupled　to　structure　the　shaft-bearing　model.　The　coupled　model　was　iterated　to　obtain　spindle　system　dynamic　parameters,　and　then　the　whirl　frequency　of　spindle　was　analyzed.　The　shaft-bearing　model　dynamics　calculation　process　was　set　up,　and　the　support　stiffness　and　whirl　frequency　of　spindle　was　researched　in　different　preload　mechanism.　Theoretical　calculation　results　show　that　compared　with　the　traditional　method,　this　model　has　higher　precision　to　predict　high　speed　spindle　dynamic　characteristics　in　operation.　Adopting　reasonable　preload　method　and　selecting　proper　preload　force　is　conducive　to　improve　the　critical　frequency　of　spindle　system　in　operation.　©,　2015,　Beijing　University　of　Technology.　All　right　reserved.