An electrohydrodynamic (EHD) pump is one of the non-mechanical pumps and expected to be utilized in various micro-pumps. The EHD pump driven by an electrostriction force is expected to reduce power consumption rate and degradation in insulation property of the working fluid. We have investigated electrode structures of the EHD pump, where the electrostriction force works as a main force, by using electromagnetic and fluid dynamics simulations. The numerical results showed that ring and plate electrodes could drive the fluid efficiently with the electrostriction force. We have measured characteristics of the EHD pumps using a cyclic flow path and compared these experimental results with the simulation data. We also analized three-rod structure by the numerical simulation to be applied as miniaturized EHD pumps.