©　2015,　Higher　Education　Press　and　Springer-Verlag　Berlin　Heidelberg.　Backlash　cannot　be　always　avoided　in　mechanical　systems　because　of　wear　or　looseness.　Steady-state　vibration　may　be　induced　by　backlash　in　closed　loop　feed　drive　systems.　This　paper　presents　a　mathematical　model　of　a　servo　rotary　table,　considering　the　effect　of　backlash.　The　accuracy　of　this　model　is　verified　by　an　experiment.　The　influences　of　the　parameters,　such　as　position　controller　gain,　velocity　controller　gain,　load　and　the　magnitude　of　backlash,　on　steady-state　vibration　are　discussed.　The　steady-state　vibration　amplitude　increases　with　the　position　controller　gain,　load　and　the　magnitude　of　backlash.　The　steady-state　vibration　frequency　increases　with　the　position　controller　gain　and　the　velocity　controller　gain,　while　an　increase　in　load　leads　to　a　decrease　in　the　frequency.