Abstract: In order to obtain the characteristics of flow filed and the influence of some parameters of a synthetic jet,numerical simulations were performed in this paper.During the simulation,moving grid technique was used for modeling the periodic movement of the piezoelectric membrane so that the field of the cavity and the external flow field could be coupled computed.The flow phenomena agreed well with the experimental results.When the frequencies,diaphragms of the piezoelectric membrane and the geometrical sizes of the cavity are changed,the velocity profile of the synthetic jet changes accordingly.The results show that the simulation model is logical and the results provide theoretical foundations for the experimental parameters determination and the optimum design of the experimental parts.