To improve the performance of electrostatically actuated valveless micropump,simulation of its dynimic characteristics have been conducted by full electrostatic-mechanic-fluidic coupled model(CFM) and prescribed deformations model(PDM)respectively.By comparing the calculated results of diaphragm deflections,transient variations of central displacements,chamber pressures and flow rate of inlet/outlet,it can be concluded that the PDM has lower cost and inadequate precision,but some distorting dynamic characteristics may be resulted from;The FCM can predict the transient behaviors of the micropump quite well since the effects of electro-mechanical coupling and fluid-structural interaction have been considered,but the computation cost is much more expensive.