Piezoelectric pumps are widely applied in medical transportation, bioengineering, and mechanical lubrication. However, the backflow phenomenon of the valveless piezoelectric pump is more prominent. Therefore, this paper designed a lunular piezoelectric pump to reduce the backflow. The three-dimensional flow field of the piezoelectric pump was analyzed using ANSYS Computational Fluid X. Based on the numerical results, the design of the lunular piezoelectric pump was improved, and a new model of the piezoelectric pump with better performance was developed. A prototype was made, and an experimental verification was carried out. The experimental results show that the maximum flow rate per unit area is 404.812 µl/min and maximum back pressure is 22.3 cmH2O, which achieves the optimal performance of the pump and verifies the rationality of Computational Fluid X simulation. Thus, the performance of a pressure pump with low driving frequency can be predicted by Computational Fluid X simulation, and the structural optimization method is reliable. This research can help to broaden the application of the piezoelectric pump.