In order to find the best synthetic jet model for study of active flow control numerical simulation, outlet velocity model, single link domain model and dynamic boundary model are researched through solving the two dimensional transient reynolds average navierstokes (RANS) equations under consistent grid and boundary conditions. Three models all show good capability of capture synthetic jets' velocity. The dynamic boundary model in which the spatial distribution and time distribution of diaphragm motion are considered and the volume change rate of actuator cavity is included can accurately capture the distribution and intensity of vortices. So the dynamic boundary model is an ideal model for applications.