Detonation initiation and propagation using a hot jet in nonuniform combustible mixtures was investigated through fine structure simulations. The Mach reflection on the upper wall resulted in the formation of the Mach stem finally near the interface, which was actually a local detonation wave. The continuous collisions of the lower triple-wave point between the lower wall and the upper triple-wave point played an important role in the successful detonation initiation. The dynamic stable structure propagated at the same speed as a whole in the nonuniform supersonic combustible mixtures. After the shutdown of the hot jet, a relatively new dynamic stable structure was formed eventually in the flow field. The hot jet not only could realize the detonation initiation, but also made an impact on the detonation propagation and the formation of the final dynamic stable structure.