Tribological　properties　of　Low-pressure　nitrogen　17-4PH/316/316L　steel　sliding　against　carbon　fiber/PTFE/graphite　filled　PEEK　were　comparatively　investigated　under　synthetic　seawater　lubrication.　The　tests　were　carried　out　on　a　MCF-10　ring-on-ring　test-bed,　under　load　of　400　N　and　rotational　speed　of　1200r/min,　which　is　be　in　accord　with　the　real　working　condition　of　water　hydraulic　axial　piston　pump　developed.　The　results　showed　that　17-4PH　stainless　steel　against　CF/PTFE/graphite　filled　PEEK　exhibited　much　lower　friction　coefficient　and　better　wear　resistance　under　seawater　lubrication　than　the　other　two　groups.　The　worn　surface　morphology　were　analyzed　by　optical　microscope.　The　main　wear　mechanism　of　three　kinds　of　friction　pairs　were　abrasive　wear　and　mechanical　plugging.　It　was　observed　that　the　surface　wear　of　316/316L　stainless　steel　against　CF/PTFE/graphite　filled　PEEK　are　more　serious　than　17-4PH　stainless　steel　against　CF/PTFE/graphite　filled　PEEK.　The　experimental　outcomes　will　be　the　key　for　the　materials　selecting　of　friction　pairs　in　seawater　hydraulic　axial　piston　pump.