The arrangement, number and spacing of hemisphere-segments directly influence the pumping performance of pump. By deducing theoretical pumping flow rate, the essential reason of pumping fluid was revealed. Flow field and simulation flow rate of pump were studied with different numbers and spacings of hemisphere-segments respectively arranged in longitudinal and transverse directions. And the result shows that the changes of arrangement, number and spacing of hemisphere-segments mean that the flow resistance differences between reverse and forward flows were changed. The rules were proved that reducing the transverse spacing, appropriately increasing the longitudinal spacing and increasing hemisphere-segment quantity in proper spacing range could all enhance the pump flow rate. Finally, the simulation conclusion was verified by using pump flow rate test. The experiments were carried out by valveless pumps installed in four hemispheresegments with the same spacings of 10mm arranged in longitudinal and transverse directions, and the experimental flow rates were respectively 48.29mL/min and 50.29mL/min; the deviations between experimental and simulation flow rates were respectively 34.6% and 34.0%. The conclusion is further validated that under the same conditions, the better pumping effect can be obtained by increasing the number of hemispheresegments in transverse arrangement than that in longitudinal arrangement.