In　the　swash　plate-type　axial　piston　pump,　the　relative　motion　of　piston/cylinder　is　lubricated　and　the　fluid　in　the　displacement　chamber　is　sealed　by　the　oil　film　between　piston　and　cylinder.　The　characteristics　of　piston/cylinder　is　influenced　by　the　oil　film　directly　and　significant　to　design　and　optimize　the　piston/cylinder.　According　to　the　periodic　rule　of　piston　motion,　the　shear　stress　and　flow　rate　of　oil　film　under　different　slip　lengths　and　rotational　speeds　of　pump　in　a　period　of　work　are　analyzed　by　the　kinetic　equation,　which　is　built　on　the　Navier-Stokes(N-S)　equations　and　the　Navier-slip　boundary　condition.　During　the　suction　phase,　it　is　shown　that　the　shear　stress　near　the　piston　wall　reduces　but　the　flow　rate　increases　with　the　increasing　slip　length.　The　shear　stress　decreases　about　18%　and　flow　rate　increases　about　13.59%　when　slip　length　increases　from　1　μm　to　3　μm　at　the　maximum　velocity　of　piston.　During　the　pumping　phase,　the　larger　velocity　of　piston　results　in　the　smaller　difference　of　the　shear　stress　near　the　piston　wall　and　the　flow　rate　between　the　slip　condition　and　no-slip　condition.　Comparing　with　the　no-slip　condition,　the　shear　stress　reduces　obviously　and　the　gap　of　total　flow　rate　also　decreases　when　the　slip　length　is　1　μm　and　the　rotational　speed　of　pump　increases　from　1　500　r/min　to　4　000　r/min.　©　2018　Journal　of　Mechanical　Engineering.