The　interaction　between　the　high-pressure　gas　fuel　jet　and　the　pilot　laminar　flame　determines　the　ignition　stability　of　the　direct　injection　natural　gas　engine.　Based　on　a　constant　volume　combustion　vessel,　the　premixed　methane　was　ignited　by　spark　electrodes　to　form　the　laminar　flame,　and　the　high-pressure　methane　was　injected　into　the　under　condition　of　varied　laminar　flame　radius.　By　high-speed　photographic　schlieren　method,　the　influences　of　methane　injection　delay　time　τ　on　the　premixed　ignition　flame　were　tested.　The　results　show　that　the　methane　injection　delay　time　τ　determines　the　development　of　the　equivalent　flame　radius　R　of　the　premixed　ignition　flame.　The　R　increases　as　τ　increases.　The　effect　of　the　jet　on　the　laminar　flame　is　related　to　the　equivalent　flame　radius　when　the　jet　just　contacts　with　the　laminar　flame,　and　there　is　a　critical　equivalent　flame　radius　R0.　As　R0,　the　jet　blows　off　the　premixed　flame.　As　R=R0,　the　methane　jet　just　blows　off　the　premixed　flame,　but　it　is　ignited　by　the　premixed　pilot　flame　with　a　speed-up　flame　propagation　velocity.　Once　R＞R0,　the　methane　jet　is　easy　to　be　successfully　ignited　by　the　pilot　flame　to　propagate　as　strong　turbulent　combustion　flame.　At　the　same　time,　the　premixed　flame　maintains　its　laminar　flame　shape　in　the　zone　without　interacting　with　the　jet.　Thus,　both　the　laminar　flame　and　the　turbulent　flame　exist　together,　and　the　flame　propagation　velocity　increases.　©　2022,　Editorial　Office　of　the　Transaction　of　CSICE.　All　right　reserved.