Abstract: Synthetic jet actuator is a new kind of flow control technique which has become a hot topic recently. This technique has great potential in flow separation control, mixing augmentation and front vortex control. A synthetic jet actuator was micro-fabricated and the flow characteristics has been studied by using hot-wire anemometer in this paper. The distribution of streamwise & spanwise velocity and swept frequency characteristics were given through experiment. The experimental data has verified its effectiveness. It is shown that the Helmholtz frequency is 425 Hz, and mechanical resonance frequency of PZT diaphragm is 850 Hz. And the maximum of centerline velocity is not located at the outlet of actuator. The research is a contribution to the optimization of synthetic jet actuators.