In order to analyze the influence of the magnitude of flow resistance and its variable rules of hemisphere-segmentbluff-body (HSBB) on pump output performance in a valveless piezoelectric pump with HSBB,experimental research on the acting law of HSBB is carried out. The longitudinal flow cover coefficient and the flow resistance coefficient calculation formula are established. Then, the flow cover resistance acting law of multiple hemisphere-segments in longitudinal alignment is obtained. Finally, the longitudinal relational expression of any number of hemisphere-segments is established, and the validity of the expression is validated based on flow resistance and pump flow experimental research of hemisphere-segments in longitudinal alignment. The maximum pump flow of 43.89 ml/min is obtained at driving voltage 120 V and frequency 6 Hz with four hemisphere-segments in the pump. This experimental flow variation trend is consistent with the theory. This researchshows that longitudinal flow resistance coefficient relational expression of hemisphere-segments is available for the calculation of flow resistance and pump flow of the valveless piezoelectric pump with HSBB. The number of hemisphere-segmentsis positively correlated with pump flow. The conclusion has practical significance for analyzing and adjusting pump flow.