The　vigorous　development　of　marine　engines　fueled　by　natural　gas　can　effectively　support　the　reform　of　energy　structures　in　the　field　of　ship　power,　aligning　with　the　global　trend　toward　sustainable　development　and　green　shipping.　However,　the　presence　of　knock　significantly　hinders　the　improvement　of　engine　thermal　efficiency.　Therefore,　studying　the　knock　mechanism　in　natural　gas　engines　is　not　only　crucial　for　enhancing　engine　power　and　economy　but　also　for　advancing　the　transition　to　cleaner　and　more　sustainable　energy　sources　in　the　maritime　industry.　In　this　paper,　via　a　2D　numerical　model,　the　dominant　role　in　the　knock　mechanism　of　stoichiometric　methane　combustion　in　a　combustion　chamber　of　a　rapid　compression　machine　(RCM)　is　revealed.　It　further　establishes　the　association　mechanism　between　constant-volume　combustion　and　pressure　wave　suppression　at　high　temperatures.　The　results　show　that　the　knock　is　caused　by　the　end-gas　auto-ignition.　The　increase　in　initial　temperature　can　significantly　change　auto-ignition　modes　and　combustion　modes,　but　initial　pressure　has　little　effect　on　this.　The　increase　in　initial　temperature　will　inhibit　the　strength　of　pressure　waves,　and　the　increase　in　initial　pressure　cannot　significantly　increase　the　strength　of　pressure　waves.　The　main　cause　why　auto-ignition　occurs　earlier　is　not　due　to　the　increase　in　the　strength　of　pressure　waves,　but　the　decrease　in　the　required　increase　in　temperature　to　attain　ignition　temperature　caused　by　the　increase　in　initial　temperature.　The　peak　pressure　is　affected　by　the　initial　pressure　on　the　left　wall　before　auto-ignition　and　the　increase　in　pressure　on　the　left　wall　at　low　to　medium　initial　temperature.　The　pressure　oscillation　amplitude　is　positively　correlated　to　the　increase　in　pressure　on　the　left　wall.　Constant　volume　combustion　will　occur　at　a　high　initial　temperature.　The　increase　and　decrease　in　pressure　are　very　uniform　which　will　lead　to　the　decrease　in　the　pressure　oscillation　amplitude.　The　peak　pressure　depends　on　the　influence　of　initial　temperature　and　pressure　on　the　increase　in　pressure　produced　by　constant　volume　combustion.