Abstract: A piston-typed actuator system is designed to study the characteristics and influence factors of synthetic jet.An experiment is conducted in the high speed wind tunnel to investigate the effect of synthetic jet on aero-acoustic noise suppression of the cavity flow field.Results indi-cate that the synthetic jet actuator is reliable and reasonable,which can produce very high speed jet with the maximum of plus velocity reaching about 160m/s.The frequency of the generated synthetic jet is consistent with the actuator excitation frequency.Some factors,such as the fre-quency of the actuator,the distance of the piston stroke and the shape of the jet exit,may exert great influence on the synthetic jet velocity.Synthetic jet characteristics are insensitive to the thickness of the jet exit.The aero-acoustic noise suppression effect of this flow control method on the cavity flow field depends strongly on the Mach number.Aero-acoustic environment of the cavity can be improved by using synthetic jet as a flow control method at transonic speed.But it is basically ineffective at supersonic speed.