Risk　assessment　of　hydrogen　energy　technologies　is　a　necessary　condition　for　the　arrival　of　a　hydrogen　energy　economy　society.　Currently,　most　methods　for　detecting　hydrogen　leaks　use　a　single　concentration　or　pressure　sensor.　Structural　visualization　and　parametric　diagnosis　of　complex　flow　fields　cannot　be　solved　simultaneously　by　a　single　detection　method.　The　main　objective　of　this　work　is　to　propose　an　advanced　optical　detection　method　to　simultaneously　monitor　the　outlet　pressure　and　density　field　distribution　during　hydrogen　leakage.　For　the　detection　of　the　density　field　distribution,　we　use　double　propagation　of　the　laser　beam　in　the　hydrogen　jet　to　improve　the　phase　sensitivity　and　relay　imaging　of　the　object　between　each　pass　to　maintain　spatial　resolution.　Error　analysis　shows　that　the　error　of　our　proposed　method　is　2.47　%,　which　is　within　the　error　tolerance.　The　sensitivity　analysis　shows　that　our　detection　sensitivity　is　twice　that　of　the　conventional　Mach-Zehnder　interferometer.　For　the　detection　of　outlet　pressure,　we　propose　a　mathematical　model　in　which　the　half-length　axis　of　the　laser　spot　is　linearly　related　to　the　outlet　pressure　and　use　the　deformation　of　the　laser　beam　in　the　hydrogen　jet　to　detect　the　outlet　pressure.　The　results　show　that　the　hydrogen　jet　can　be　regarded　as　a　gas-phase　lens　when　detecting　the　outlet　pressure,　and　the　deformation　of　the　laser　beam　profile　in　the　horizontal　direction　increases　linearly　with　the　increase　of　the　jet　pressure.　The　results　of　the　study　can　provide　a　reference　for　the　detection　of　accidental　hydrogen　leakage　and　the　improvement　of　hydrogen　safety　regulations.