Summary Effective control of mode transition is one of the key technologies for dual‐mode scramjet. In this study, a 3‐dimensional unsteady Reynolds‐averaged Navier‐Stokes modeling was used to investigate the effects of equivalence ratio, inflow temperature, and pilot hydrogen on transient process of mode transition in a dual‐mode scramjet combustor. The isolator entrance Mach number was 2.5, and the fuel of vaporized kerosene was used in the combustor with pilot hydrogen. The results showed that during mode transition from ram mode to scram mode induced by reducing the equivalence ratio of kerosene, the disappearance of the high‐pressure zone around the kerosene injector was the sign of approaching the achievement of mode transition. The leading edge of the shock train moved downstream and the strength of shock train was significantly weakened. During this process, the distribution of heat release zone transformed from scattered along the combustor to being concentrated in the cavity. Then, the opposite process was studied when the inflow temperature was reduced from 1750 to 1000 K while the equivalence ratio was kept the same. The thickness of shear layers originated from the fuel injectors significantly increased. Altering the amount of pilot hydrogen can significantly influence the flow field in the combustor. It showed that the increase of pilot hydrogen could shield the kerosene vapor entering into the high‐temperature zone in the cavity and hindered the formation of concentrated heat release. Thus, the overall heat release became more dispersed.