This　paper　based　on　the　flow　field　numerical　simulation　method　to　analyze　the　valves　used　for　space　instrumentation　,　the　flow　field　of　high-pressure　unloading　valve　was　numerical　simulation　upon　different　structural　parameters　,　thus　it　achieved　the　result　of　the　pressure　and　velocity　field.　the　effect　of　flow　field　and　pressure　velocity　characteristic　by　the　structural　parameters　was　analyzed.　The　results　of　the　numerical　simulation　was　verified　by　the　experimental　test,　so　the　results　provided　some　references　for　the　unloading　valve　optimum　structure　design　and　performance　improvement.　©　2010　IEEE.