In order to improve the output performance of the piezoelectric pump, a flexible duckbill valve piezoelectric pump is designed according to the duckbill structure form. Firstly, the structure and working principle of the flexible duckbill valve piezoelectric pump are described; secondly, the output flow rate and output pressure of the flexible duckbill valve piezoelectric pump are theoretically analyzed; finally, the flexible duckbill valve piezoelectric pump prototype is made, and the change rules of the flow rate as well as the difference between the inlet and outlet pressures are investigated. The experimental results show that the maximum pressure difference between the inlet and outlet of the flexible duckbill valve piezoelectric pump can be up to 15.5 kPa driven by 220 V, 45 Hz sinusoidal alternating current; the maximum flow rate of the flexible duckbill valve piezoelectric pump is 39 mL/min driven by 220 V, 55 Hz sinusoidal alternating current. The results verify that the flexible duckbill valve piezoelectric pump has good conveying capacity.