Tribological　behaviors　of　30　vol%　carbon　fiber-reinforced　polyetheretherketone　(PEEK-1)　and　30　vol%　carbon　fiber/PTFE/graphite-reinforced　polyetheretherketone　(PEEK-2)　sliding　against　AISI630　steel　under　seawater　lubrication　were　investigated　comparatively　with　a　ring-on-ring　contact　test　apparatus.　The　results　revealed　that　PEEK-2　had　a　lower　friction　coefficient　and　much　better　wear　resistance　than　PEEK-1,　especially　under　a　relatively　heavy　load.　Furthermore,　PEEK-2　exhibited　much　better　friction　and　wear　properties　under　seawater　lubrication　than　under　dry　friction,　and　it　was　slightly　inferior　to　that　under　pure　water　lubrication　due　to　the　corrosive　effect　of　seawater　on　the　surface　of　AISI630　steel.　Additionally,　the　worn　surface　morphology　of　PEEK　composites　and　AISI630　steel　were　obtained　through　scanning　electron　microscopy　(SEM)　and　optical　microscopy,　respectively.　The　main　tribological　mechanisms　of　the　friction　pair　under　seawater　lubrication　were　abrasive　wear　and　indirect　corrosive　wear.　The　corrosion　of　the　AISI630　surface　caused　by　Cl-　and　SO4-　of　seawater　performed　more　dramatically　than　the　lubricating　effect　of　Ca2+　and　Mg2+　on　the　contacted　surface　and　deteriorated　the　tribological　behaviors　of　the　matched　material　to　some　extent.　This　research　will　provide　guidance　for　materials　screening　of　key　friction　pairs　in　seawater　hydraulic　piston　pumps/motors.