Abstract: Periodicity advance model of 1-D slab symmetry detonation wave is investigated. The advance of an 1-D slab symmetry detonation wave shows a periodicity in structure. The velocity of the wave ahead (in which no reaction takes place) is subsonic for the wave after it, and it is attenuation by rarefaction wave catching up. Detonation wave heats up the explosive and triggers the "chemical shock waves", it catches up the shock wave ahead and increases to its initial parameters. Thus, a whole period has been accomplished.