Abstract: Abstract: Please compose your abstract in English here. Natural gas hydrogenation technology has been gradually used in pipeline transportation, but hydrogen/methane is prone to leakage and explosion accidents. This works uses a 20 L spherical device to study the effects of hydrogen ratio and adding CO2 on the explosion characteristics of methane. The results show that the hydrogen ratio has a promoting effect on the explosion pressure and flame propagation speed of methane, among which the maximum explosion pressure rise rate is the most significant. Carbon dioxide has an inhibitory effect on the explosion pressure and flame propagation speed of the mixed gas, but the suppression effect on pressure parameters with high hydrogen doping ratio is weak. As the hydrogen ratio increases, the hydrodynamic instability and thermal mass diffusion instability of the flame first increase and then weaken. Carbon dioxide has an inhibitory effect on hydrodynamic instability and a promotion effect on thermal mass diffusion instability. It can be seen from the reaction kinetics analysis that as the hydrogen doping ratio increases, the flame laminar burning velocity and adiabatic flame temperature gradually increase, the concentration of active free radicals and the product generation rate increase significantly, and the mixing of hydrogen changes the reaction path of methane. When XH2>0.5, the most sensitive reaction step in the forward direction changes from R38 to R84. Carbon dioxide can reduce the laminar burnin.