A polymer microfluidic pump has been developed using electrostrictive poly(vinylidene fluoride-trifluoroethylene) based polymer, which possesses a large electrostrictive strain (5-7%) and high elastic energy density (1 J/cm3), as the driving microactuator. The microfluidic pump was realized by integrating a nozzle/diffuser type fluidic mechanical-diode structure with the polymer microactuator, which shows an actuation deflection of 80 mm for a pumping chamber of 2.2x2.2 mm2. The microfluidic pump could pump methanol at a flow rate of 25 mL/min at 63 Hz with a backpressure of 350 Pa. The flow rate of this pump could be easily controlled by external electrical field. Results from both analytical and numerical analysis show that, due to the high load capability of the microactuator, the frequency response of this nozzle/diffuser pump is mainly limited by the resonance of the fluid in the fluid channel.