Annular　gap　throttle　has　been　used　in　water　hydraulic　slide　valve　which　makes　the　hydraulic　full-bridge　network　of　the　water　hydraulic　servo　valve　different　from　that　of　traditional　hydraulic　servo　valve　with　fixed　orifice.　Based　on　liquid　resistance　theory　and　hydraulic　bridge　theory,　the　load　pressure　characteristics,　pressure　sensitivity　and　static　characteristic　parameters　have　been　analyzed　by　the　research　of　hydraulic　full-bridge　network　constituted　by　annular　gap　throttle　and　clearance　throttle　between　flapper　and　nozzle.　The　results　show　that　the　load　pressure　characteristics　of　the　hydraulic　full-bridge　in　water　hydraulic　servo　valve　keep　fine　linear　relationship　with　flapper　displacement,　but　the　pressure　sensitivity　decreases　in　the　normal　working　range　of　servo　valve.　However,　the　pressure　sensitivity　can　achieve　a　reasonable　value　by　the　improvement　of　hydraulic　full-bridge.