The　mixture　of　ammonia　(NH3)　and　hydrogen　(H2)　is　the　potential　alternative　fuel　for　internal　combustion　engines　(ICEs).　The　turbulent　jet　ignition　(TJI)　system　can　provide　high　ignition　energy　and　turbulent　disturbance　to　promote　the　combustion　of　the　mixture　for　NH3/H2　ICEs.　Therefore,　the　combustion　characteristics　of　NH3/H2/air　under　passive　TJI　conditions　were　experimentally　studied　in　the　present　study.　The　experiment　was　conducted　in　a　constant　volume　combustion　bomb,　and　the　effect　of　fuel　composition　and　equivalence　ratio　was　investigated.　The　experimental　results　show　that　compared　to　spark　ignition,　the　combustion　of　NH3/H2　can　be　effectively　improved　by　using　TJI,　especially　under　high　NH3　fraction　conditions.　The　addition　of　H2　has　a　significant　positive　effect　on　the　ignition　and　combustion　performance.　With　the　addition　of　H2,　the　ignition　delay　and　combustion　duration　decrease　evidently.　And　the　H2　addition　is　beneficial　for　improving　the　ignition　mechanism　and　achieving　flame　ignition.　In　addition,　poor　ignition　performance　may　occur　under　rich　conditions　due　to　the　fluid-dynamic　quenching　of　the　jet.　However,　the　high　flame　propagation　rate　on　the　rich　side　still　leads　to　lower　combustion　duration.　Moreover,　increasing　the　orifices　number　appropriately　can　enhance　the　ignition　and　combustion　performance.　The　jet　strength　is　weakened　by　the　increased　total　orifice　area　and　the　ignition　of　NH3/H2　can　be　improved.　©　2024　Elsevier　Ltd