Due　to　the　inconformity　of　assembly　stress　and　thermal　expansion　transfiguration　in　the　internal　components　of　shaft　systemthe　precision　angular　contact　ball　bearing　could　be　ap　plied　into　the　combined　loads　consisting　of　axial　load　radial　load　and　torque　which　affected　both　the　dynamic　characteristics　of　bearing　and　the　service　performance　of　precision　shaft　system.　According　to　the　relationship　of　interaction　and　relative　position　between　the　rolling　element　and　bearing　tracka　fivedegreeoffreedom　quasistatic　model　considering　the　effects　of　centrifugal　forcegyroscopic　torque　and　other　nonlinear　factors　was　establishedand　the　calculation　model　of　bearing　stiffness　was　improved　by　the　principle　of　stepbystep　search　method.　The　evolution　ary　regularity　of　dynamic　characteristics　for　precision　angular　contact　ball　bearings　was　investigat　ed　in　combined　loads.　The　results　indicated　that　the　axial　load　could　decrease　the　difference　be　tween　ballinner　raceway　contact　angle　and　ballouter　raceway　contact　angle　and　suppress　the　stiffness　softening　caused　by　the　increase　of　speed.　When　the　torque　and　radial　force　were　applied　separately　the　fluctuation　range　of　contact　angle　and　contact　force　increased　and　the　bearing　stiffness　along　the　direction　of　loads　also　increasedwhile　the　stiffness　decreased　perpendicularly　to　this　direction.　In　the　condition　of　combined　loadsthe　torque　would　restrain　the　fluctuation　of　load　distribution　due　to　the　radial　loadand　improve　the　loading　capacity　and　service　life　of　preci　sion　ball　bearing.　©　2022　BUAA　Press.　All　rights　reserved.