For the application of the compact large flowrate pump to the portable products,a compact piezoelectric hydraulic pump actuated by a round piezoelectric bimorph plate is introduced in this study. Compared with a conventional pump,the chamber volume change of the proposed pump increases by more than 50% in one vibrating cycle. A prototype pump with dimensions of 42 mm×42 mm×14 mm was developed and excited by a piezoelectric bimorph and the PZT with a diameter of 25 mm×0.2 mm. The prototype can pump water at a flow rate of 800 mL/min under a driving voltage of 320 V at 380 Hz.