Hydrogen　has　the　widest　flammable　range,　the　fastest　flame　propagation　speed,　and　the　lowest　ignition　energy,　so　its　safety　needs　special　attention　before　the　wide　application　of　hydrogen　energy.　The　main　objective　of　this　work　is　to　propose　a　new　method　to　evaluate　hydrogen　jet　pressure　by　using　a　Helium–Neon　laser　through　the　jet.　A　mathematical　model　was　proposed,　which　describes　the　deformation　of　the　laser　beam　profile　passing　through　an　axisymmetric　circular　hydrogen　jet　pressure　flow　field　in　detail.　This　research　attempts　to　apply　the　expression　of　density　Gaussian　distribution,　ideal　gas　equation,　and　Gladstone　Dale　equation　to　disclose　the　deformation　of　laser　beam　profile　under　different　outlet　conditions.　The　experimental　uncertainty　is　about　3　×　10−3.　A　non-contact　optical　experimental　system　is　established　to　visually　measure　the　density　gradient　distribution　of　the　gas　jet.　Our　findings　show　that　the　hydrogen　jet　can　be　regarded　as　a　gas-phase　lens,　and　the　deformation　of　the　laser　beam　profile　in　the　horizontal　direction　increases　linearly　with　jet　pressure.　Finally,　the　preliminary　results　of　calculations　of　the　spot　area　with　the　theoretical　model　were　presented　and　compared　with　the　images　of　the　laser　beam　profile　passing　through　the　jet　in　the　experiment.　The　theoretical　model　gave　similar　results　and　the　overall　agreement　with　the　experiment　was　satisfactory.　Our　technology　exhibits　high　sensitivity　in　the　measurement　of　hydrogen　leakage　pressure,　providing　a　theoretical　basis　for　non-contact,　non-damaged,　high-response,　and　high-sensitivity　detection　of　hydrogen　leakage.　©　2022　Hydrogen　Energy　Publications　LLC