Abstract: A gas explosion travel experiment was conducted in a closed pipeline of DN700 mm with gas-air mixed gas under the conditions of the different ignition energy.The experiment results showed that the flame travel speed of the gas explosion from the explosion location would be steadily increased with the travel distance i ncreased and the max value of the flame travel speed would be reached at the location near the exit. The higher ignition energy was and the higher flame travel speed w ould be.When the ignition was certain, the flame travel speed of gas explosion and pipeline length and diameter ration would be in a logarithmic function relationship.W hen the pipeline length and diameter ratio was certain, the flame travel speed of gas explosion and ignition energy would be in a quadratic function relationship.