Abstract: A theoretical calculation is made of the nonequilibrium dissociation of the diatomic molecule with the vibration-dissociation coupling behind a strong shock wave front.The distinguishing feature of this work is to take the molecular fundamental parameters as the starting point for calculation.The master equation method is applied to study the coupling between vibrational excitation and dissociation.The vibrational transition probabilities are calculated with the SSH theory.In the neighborhood of the dissociation limit,the multi-quantum transitions are taken into account and the effect of atom recombination is considered.In a O2-Ar mixture,the variation of many of the physical quantities of O2 molecule behind a primary shock front with time are calculated out,such as the vibrational energy level distribution,the vibrational relaxation time,the dissociation incubation time,the dissociation product concentration and the dissociation rate coefficient.The calculated results are found to be in a od agreement with those experimental data given by Camac and Wray,respectively.It is demonstrated in the calculation that a quasi-steady state emerges at the late stage after the shock passage during which the vibrational energy level distribution persists almost constant,Park's model underestimates the nonequilibrium dissociation rate coefficient and Hansen's model overestimates the nonequilibrium dissociation rate coefficient.