Sliding　bearing　pair　is　one　of　the　important　friction　pairs　within　water　hydraulic　axial　piston　pump,　which　can　result　in　significant　influences　on　the　pump＇s　performance.　Generally,　owing　to　the　characteristics　of　low　viscosity　and　poor　lubrication　of　water,　the　sliding　bearing　will　operate　under　condition　of　dry　or　mixed　lubrication,　leading　to　a　severe　adhesives　wear　and　material　softening.　In　order　to　investigate　the　flow　field　of　the　sliding　bearing　in　hydrodynamic　condition,　the　effects　of　the　water　film　pressure　distribution,　load　carrying　capacity　changing　with　radial　clearance　and　width-radius　ratio　of　the　sliding　bearing　pair　have　been　simulated　through　MATLAB.　And　a　suitable　material　combination　of　the　sliding　bearing　pair　was　selected　though　a　custom-manufactured　friction　and　wear　test　rig.　Based　on　the　theoretical　and　experimental　studies,　an　appropriate　structure　of　the　sliding　bearing　within　water　hydraulic　axial　piston　pump　was　designed.　The　loading　experiments　for　the　developed　water　hydraulic　axial　piston　pump　assembled　with　two　different　flanges　have　been　conducted　at　a　water　hydraulic　component　test　rig.　The　experimental　results　revealed　that　the　volumetric　efficiency　and　noise　characteristics　of　the　pump　are　remarkably　improved　when　the　sliding　bearing　work　under　hydrodynamic　lubrication　condition　in　comparison　with　dry　lubrication　condition.　The　research　results　have　laid　the　foundation　for　the　development　and　improvement　of　the　water　hydraulic　axial　piston　pump.