Ammonia　(NH　3　)　and　hydrogen　(H　2　)　mixture　are　expected　to　replace　traditional　fossil　fuels　in　the　transportation　industry　to　achieve　zero-carbon　emissions.　Adopting　turbulent　jet　ignition　(TJI)　is　a　reliable　way　to　enhance　the　ignition　and　combustion　of　NH　3　/H　2　.　The　present　study　aims　to　explore　the　effects　of　initial　pressure　and　temperature　on　the　ignition　and　combustion　characteristics　of　NH　3　/H　2　ignited　by　TJI.　It　can　be　found　that　the　increased　initial　pressure　reduces　the　jet　velocity.　Due　to　the　joint　effect　of　weakened　turbulence　and　inherent　flame　propagation　characteristics　caused　by　the　elevated　pressure,　the　combustion　duration　is　extended.　However,　the　ignition　performance　can　be　enhanced　by　increasing　the　initial　pressure.　Improvement　is　reflected　in　the　emergence　of　flame　ignition　mechanisms　and　the　obvious　radial　propagation　of　jet　flames　in　early　development.　The　increase　in　initial　temperature　slightly　increases　the　peak　jet　velocity,　while　the　auxiliary　H　2　in　active　mode　will　reduce　the　sensitivity　of　jet　velocity　to　the　initial　temperature.　Although　the　increased　initial　temperature　has　shown　the　promotion　for　achieving　rapid　ignition　and　combustion,　there　is　no　significant　improvement　in　the　ignition　mechanism,　the　ignition　is　caused　by　accumulated　heat　and　radicals　provided　by　the　reacted　jet.