In　order　to　improve　the　performance　of　spark-ignition　engine　fueled　with　natural　gas,　it　is　necessary　to　analyze　the　effect　of　intake　temperature,　intake　pressure,　equivalence　ratio,　jet　ignition　and　compression　ignition　(auto-ignition)　in　the　methane　combustion　process.　A　series　of　combustion　tests　were　carried　out　to　study　the　combustion　characteristics　of　pre-mixed　mixture　of　CH4-Air　in　the　constant　volume　combustion　chamber　(CVCC).　Some　test　results　were　obtained　by　flame　propagation　photo　and　gas　pressure　measurement.　Owing　to　a　built-in　adaptor　with　hole,　higher　flame　propagation　speed,　higher　combustion　peak　pressure　value　and　higher　combustion　stability　are　available.　In　some　conditions,　because　of　flame　trap　effect,　compression　ignition　(auto-ignition)　occurs　in　the　lower　combustion　chamber.