The structural software ANSYS and the fluid software ANSYS CFX. were used to simulate the structural-fluid coupling of a valveless piezoelectric pump and to research its output performance. Three different kinds of valveless pumps, the pump with middle inlet, the pump with middle outlet and the pump with side inlet/outlet were designed. The structural-fluid coupling on these valveless piezoelectric pumps was simulated by the software ANSYS and the software ANSYS CFX. The simulation results show that the pump with middle outlet has the maximum output flow rate. The prototypes of the three kinds of piezoelectric pumps were fabricated and a corresponding testing system for the pumps was set up and test experiments were performed under a sinusoidal AC excitation signal of 45 V and the frequency of 0-700 Hz. The results show that the maximum output flow rates of the three kinds of valveless pumps are 3.8 ml/min, 6.0 ml/min and 4.0 ml/min, respectively. Among them the pump with middle outlet has the maximum output flow rate, which is consistent with the results of the structural-fluid coupling simulation and verifies that the simulation method proposed by this paper can guide the design of piezoelectric pumps.