Reliability　test　of　seawater　hydraulic　pumps　in　deep-sea　environment　is　a　prerequisite　for　its　application　in　deep-sea　equipment　such　as　underwater　robot　and　hydraulic　buoyancy　adjusting　system.　It　is　essential　to　explore　the　deep-sea　test　method　and　device　for　seawater　hydraulic　pumps.　Based　on　the　previous　studies,　a　deep-sea　simulated　experiment　devices　is　developed　to　test　seawater　hydraulic　pumps,　which　is　composed　of　high　pressure　cabin,　pressure　loading　system,　water　circulating　and　cooling　system　and　etc.　Especially,　the　cabin　uses　a　quick-opening　&　clamping　structure,　which　is　easy　to　putting　in　and　out　the　test　equipment.　Water　pressure　inside　the　cabin　can　be　automatically　loaded　and　replenished,　and　its　maximum　value　can　reach　to　45　MPa.　Working　condition　of　the　tested　pump　is　simulated　through　throttle　damping,　which　is　located　in　water　circulating　and　cooling　pipes　outside　the　cabin.　The　parameters　such　as　water　temperature　and　pressure,　loading,　and　flow　rate　can　be　synchronously　transmitted　to　the　data　acquisition　system　during　the　test　process.　The　tester　can　successfully　complete　seawater　hydraulic　pump　testing　work　in　seawater　environmental　depth　of　4500　m.　The　research　above　can　provide　guidance　for　testing　and　application　of　seawater　hydraulic　pump　in　deep-sea　environment.　©　2015　IEEE.