Abstract: Considering the shortcomings and incompetence of conventional piezoelectric synthetic jet actuator(PE-SJA),a novel multi-diaphragm PE-SJAdesign was proposed in this paper and some detailed experimental studies were carried out upon it.By using the hotwire anemometry,the optimum resonance frequency of the actuator was obtained through measuring the velocity magnitude at a fixed position on the axis of the orifice exit flowfield at different frequencies.Then the orifice exit velocities with different numbers of diaphragm were measured,analyzed and compared,which showed that at the axis of the orifice exit flowfield the averaged and peak velocities of one-diaphragm PE-SJAwas only the half of those of the five-diaphragm PE-SJA.But the performance of three-diaphragm PE-SJAwas almost the same as that of the five-diaphragm PE-SJA,which suggested that although the performance of the PE-SJAincrease with the number of the piezoelectric diaphragm,it did not occur in a linear way.PIVwas also used to obtain the structure of vortex of the flowfield.