A novel driving theory on the electrohydrodynamic (EHD) pump driven by traveling electric fields without the temperature gradient is proposed. The equations of the generating pressure and the flow rate are derived. The EHD micropump is fabricated by micromachining technology and tested. The channel heights are 50$mu extrm{m}$, 100$mu extrm{m}$ and 200$mu extrm{m}$ are respectively an the channel width is 3 mm. The spacing and width of the electrodes are both 40$mu extrm{m}$. The maximum pressure is 70.3 Pa, 35.4 Pa and 17.2 pa at he frequency of 0.2Hz for each channel height (50$mu extrm{m}$, 100$mu extrm{m}$ and 200$mu extrm{m}$) and the maximum flow rate is 0.90x10ulcorner ${mu}$$ell$/min, 1.88x10ulcorner ${mu}$$ell$/min and 4.85x10ulcorner ${mu}$$ell$/min at the frequency of 0.4H for each channel height.