High-pressure　gas　fuel　direct　injection　(HPDI)　technology　benefits　the　engine　with　high　efficiency　and　great　output　power.　During　the　initial　ignition　process　of　the　gas　fuel　jet　ignited　by　the　pre-ignition　flame,　the　gas　jet　interacts　with　the　pre-ignition　flame,　and　causes　important　effects　on　the　flame　propagation　and　stability.　This　work　aims　to　investigate　the　effects　of　the　high-pressure　gas　fuel　(methane)　jet　on　the　premixed　methane　flame　with　an　equivalence　ratio　of　0.7　in　a　constant　volume　bomb　(CVB)　based　on　a　three-dimensional　numerical　model.　The　results　indicate　that　there　is　a　complex　interaction　between　the　high-pressure　methane　jet　and　the　premixed　flame.　The　dominant　combustion　mode　within　the　CVB　changes　from　the　premixed　flame　surface　to　the　diffusion　flame　surface,　which　results　in　two　different　combustion　behaviors　in　different　regions　along　the　methane　jet　direction,　that　is,　primary　ignition　and　secondary　ignition.　The　methane　jet　flame　development　is　divided　into　three　regions,　that　is,　laminar　combustion　laminar-turbulent　combustion,　turbulent　combustion.　Reynolds　number　of　the　main　region　of　turbulent　combustion　ranges　within　Re　=　2300-6000,　which　means　that　this　flame　is　a　small-scale　turbulent　flame.　These　findings　contribute　to　understanding　the　combustion　characteristics　under　high-pressure　direct　injection　natural　gas　engine　conditions,　particularly　in　lean　burn　conditions,　providing　valuable　insights　for　natural　gas　lean-burn　flame　stability.