Abstract: Three processes of ignition were investigated by usinghigh speed camera and schlieren system with the inflow condition ofMa=2.64, T_0=1483K, P_0=1.65MPa, T=724K, andP=76.3kPa, which are autoignition ofhydrogen injection, the spark igniting hydrogen and the pilot flame ignitingthe kerosene in a constant area model scramjet combustor. The flamepropagation and shocktrains evolution in the combusotr was gained, whichrevealed that the flame originated from the downstream of the combustor,then propagated to upstream untill the whole combustor was ignited. Theresults also showed that flow velocity of combustor and installation schemeof flame holders will extremely affect the ignition delay or occurringposition of ignition. Furthermore, the fuel residence time will be increasedby using more cavity flameholders, which was benificial to fuelautoignition.