The explosion of premixed gas in a closed vessel is very complicated.In order to study the effect of ignition position on the explosion characteristics of methane/air premixed gas,the central ignition explosion experiment with 10 vol.% methane concentration in a 1 m3 closed spherical explosive vessel was carried out under an initial pressure of 101 kPa and an initial temperature of 300 K.Besides,the effect of different ignition positions(center ignition,0.5R ignition,R ignition) on the explosion characteristics of methane/air premix in the vessel was studied by LES turbulence model and Zimont combustion model of the Fluent numerical simulation software.It includes flame structure evolution,explosion temperature,explosion pressure and explosion pressure rise rate.The results show that the flame expands around until the wall and profile of the vessel gradually change from the initial “left thin and right thick” to the “left raised sharp angle” and gradually stretch from the “circular arc” to the “sharp shape” to the left when the flame is ignited at the center,0.5R and R.And then,there is a temperature gradient in the temperature field at different ignition positions.The heating law is continuously released from the energy of the ignition center,and the temperature continuously accumulates and rises.Furthermore,the variation trend of explosion pressure under different ignition positions is basically the same.The final maximum explosion pressure is stable at about 766 kPa due to the wall insulation.Finally,the rise rate of the maximum explosion pressure in the center ignition is the highest,which is 94.5% and 141.8% higher than that in 0.5R ignition and R ignition,respectively.