Abstract: 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.