The　direct　contact　condensation　(DCC)　of　submerged　vapor　jet　in　liquid,　which　has　high　heat　and　mass　transfer　efficiency,　is　widely　applied　in　nuclear　power　generation,　chemical　engineering　and　aerospace.　The　pressure　pulse　generated　by　hydraulic　instability　during　DCC　may　create　periodical　impulsive　loads　on　the　solid　wall.　It　is　important　to　evaluate　pressure　pulse　characteristics　using　a　wide　range　of　inlet　properties　to　avoid　risky　flow　pattern　regions　where　pressure　pulses　are　strong.　This　paper　presents　an　experimental　study　of　the　interface　dynamics　and　pressure　pulse　of　DCC　using　subsonic　and　supersonic　steam　jets　condensing　in　water　in　a　horizontal　channel.　The　results　reveal　that　pressure　pulses　in　unstable　region　are　caused　by　the　contraction　and　expansion　of　the　steam-water　interface,　while　pressure　pulses　in　stable　region　are　caused　by　Kelvin-Helmholtz　(KH)　instability.　Flow　pattern　transition　is　found　to　affect　pressure　pulse　intensity.　Pressure　pulse　intensity　is　minimal　at　the　transition　between　the　stable　region　and　unstable　region.　The　correlations　of　pressure　pulse　intensity　in　unstable　and　stable　regions　are　given,　respectively.　The　results　of　this　study　can　inform　the　design,　safe　operation,　and　lifespan　evaluation　of　equipment　in　various　industrial　applications　that　involve　DCC.　©　2021　Elsevier　B.V.