Abstract: A valveless piezoelectric pump using synthetic jet was presented,and a continuous flow was realized by an optimized structure. This paper introduces the structure, working principle and characteristics of this micro-pump. A three-dimensional model was established,and numerical simulation was used to analyze its principle and performances. Results of calculation show that the height of the chamber,import and export diameter are three main factors affecting the performance of the pump.Distance between the import and the export has smaller effect on flow,the same as the diameter of chamber. In different speed ranges,the obtained calculation results of two medium air and water show that the difference between them is great at low speeds and little at high speeds. The diameter of import is2 000 μm,diameter of outport is 1 000 μm,the height of the chamber is 3 000 μm,frequency f = 100 Hz,nozzle maximum Reynolds number Re = 750,flow rate is 24 m L/s,and the volume deformation is1. 12.