Abstract: The trigger factor of gas explosion is ignition source, starting from the ignition factor, the experimental platform of the two ignition energy of gas explosion pipes was established. The same concentration gas mixtures were detonated, and the gas explosion flame was shot with high speed camera, then the photos were analyzed by MATLAB programming. The optical characteristics of gas explosion flame were analyzed under quite different ignition energy, and it was obtained that the optical characteristics law of gas explosion for different ignition energy. Finally, the division of three stages was proposed about gas explosion of small scale pipeline.