Abstract: A valveless piezoelectric micropump based on PZT thin film is presented.Polydimethylsiloxane（PDMS） is used as the membrane and a piezoelectric disk fabricated in our laboratory is used as the actuator of the micropump.Based on the theory of diffuser/nozzle,the finite model of micropump is set up.In order to realize the bidirectional fluid-solid couple analysis for micropump,MFX-ANSYS/CFX technology to numerical simulations was utilized and optimization paramaters of the angle,the mininal width,length of diffuser and the height of the chamber were obtained.Experiments show good agreement with our simulations.