A　new　type　of　double　nozzle-flapper　water　hydraulic　servo　bridge　model　is　developed,　in　which　the　two　tandem　fixed　dampers　are　adopted　as　prepositive　dampers.　The　parameter　sensitivity　analysis　for　the　hydraulic　bridge　is　carried　out.　The　relationship　among　the　flapper　displacement,　the　spool　speed　and　the　pressure　at　the　two　ends　of　the　spool　is　investigated.　The　orthogonal　design　is　employed　to　study　the　influence　of　the　physics　factors　on　the　characteristics　of　the　hydraulic　bridge,　such　as　the　diameter　of　the　nozzle,　the　diameters　of　the　two　tandem　fixed　dampers,　the　spool　diameter　and　its　sliding　speed,　the　initial　clearance　between　nozzle　and　flapper.　The　results　reveal　that　(1)　The　smaller　initial　clearance　between　nozzle　and　flapper,　the　larger　diameter　of　spool　and　the　clearance　between　spool　and　valve　body,　the　shorter　overlap　length　of　spool　and　valve　body,　and　the　higher　system　pressure,　will　lead　to　the　better　linearity　of　the　control　characteristics　for　the　water　hydraulic　bridge;　(2)　For　hydraulic　bridge　of　water　servo　valve　including　the　two-stage　dampers,　the　smaller　first　damper　diameter,　the　larger　second　damper　diameter,　the　smaller　pipe　diameter　before　the　nozzle,　the　larger　diameter　of　spool　and　the　clearance　between　spool　and　valve　body,　will　bring　the　higher　dynamic　response　in　the　water　hydraulic　bridge.　These　research　results　will　lay　the　theoretical　foundation　for　the　development　of　water　hydraulic　servo　valve.