The effect of one obstacle on the explosion intensity of a methane-air mixture in connected vessels was studied. The experimental results suggested that the blockage ratio and the position of obstacles played a great role in this intensity. The obstacles could increase the reaction speed. When the blockage ratio reaches a certain value, the disturbance effect on the flame is at its highest, and the turbulence intensity and explosion intensity are at their strongest. If the obstacle's blockage ratio is greater than or less than this value, the explosion intensity is weaker. If the obstacles are closer to the initiating container, the combustion pressure will rise earlier both in the initiating container and in the connecting pipe. However, the effect of the obstacle position on the peak combustion pressure is limited. The conclusions provided an important reference for the safety design of explosion venting and explosion resistance. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.