For　micro　effect　of　the　slippage　phenomenon　adjacent　to　wall　in　micro-scale　gap　flow　of　hydraulic　system,　computational　fluid　dynamics　(CFD)　method　is　applied　to　investigate　the　effects　of　wall　slip　on　flow　behaviors　in　micro-scale　gap.　The　Navier　slip　boundary　condition,　which　wall　slip　velocity　is　proportional　to　the　degree　of　slip　coefficient　and　the　local　velocity　gradient,　is　adopted　to　simulate　the　gap　flow　between　oil　sealing　sides　in　hydrostatic　bearing　system.　After　examining　consistency　of　results　between　simulation　and　theory,　the　influence　of　slip　parameter　on　gap　flow　behavior　is　implemented.　The　influence　of　wall　apparent　viscosity　coefficient,　temperature-viscosity　characteristic　and　Non-Newtonian　behavior　on　distributions　of　flow　in　gap　and　the　value　of　wall　slip　velocity　are　analyzed　deeply.　It　is　shown　that　micro-scale　gap　flow　with　slip　condition　is　different　from　that　of　no-slip　boundary　condition,　when　the　wall　material　property　coefficient　ø=0.01,　the　faster　of　the　wall　slip　velocity　and　more　uniform　of　velocity　in　flow　gap,　and　the　temperature-viscosity　characteristic　is　the　significant　factor　affecting　gap　flow　distribution　and　slip　velocity.　©　2011　Journal　of　Mechanical　Engineering.