For　the　behaviors　of　micro-fluidics　in　cavity　micro-flow,　a　CFD　numerical　simulation　is　adopted　to　investigate　the　slip　effects　on　cavity　micro-flow.　In　addition,　a　new　slip　model　based　on　the　concept　of　boundary　layer　thickness　was　derived　theoretically　and　tested.　It＇s　found　that　boundary　wall　with　the　Navier　slip　condition　will　change　the　pattern　of　cavity　micro-flow.　In　the　case　of　pressure　driven　cavity　micro-flow,　the　slip　wall　boundary　condition　will　restrain　the　growth　and　development　of　vortex　in　the　cavity.　On　the　lid-shear-driven　cavity　micro-flow,　slip　wall　boundary　condition　could　change　the　position　and　shape　of　vortex　separation　line　under　cavity,　yet　a　stronger　degree　slip　will　promote　the　morphological　changes　of　vortex.　Meanwhile　the　new　slip　model　is　more　applicable　to　step-wall　boundary　condition,　which　will　reveal　the　process　of　slip　occurrence.　©　2011　IEEE.