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The pumping performance of valve-less piezoelectric mainly depends on the flow resistance difference between forward and reverse directions, so testing flow resistance is particularly important. Flow resistance testing device of valve-less piezoelectric pump was designed which can realize automatic or semi automatic water supply function and the measured flow range was wide. The device can be easily used to analyze and research flow action law. Hemisphere-segment valve was taken as study object and the resistance coefficient formula was derived. Flow resistances were tested respectively by traditional and novel test devices and theoretical pump flow were calculated. The deviations between theoretical and experimental flow rates were 34.38% and 117.33%, respectively. The results showed that the accuracy of flow resistance test was greatly improved by the flow resistance testing device of valve-less piezoelectric pump, which can test and analyze flow resistance, calculate pump theoretical flow and predict experimental flow.