In this work, an efficient electroosmotic pump (EOP) based on the ultrathin silica nanoporous membrane (u-SNM), which can drive the motion of fluid under the operating voltage as low as 0.2 V, has been fabricated. Thanks to the ultrathin thickness of u-SNM (similar to 75 nm), the effective electric field strength across u-SNM could be as high as 8.27 x 10(5) V m(-1) in 0.4 M KCl when 1.0 V of voltage was applied. The maximum normalized electroosmotic flow (EOF) rate was as high as 172.90 mL/min/cm(2)/V, which was larger than most of other nanoporous membrane based EOPs. In addition to the ultrathin thickness, the high porosity of this membrane (with a pore density of 4 x 10(12) cm(-2), corresponding to a porosity of 16.7%) also contribute to such a high EOF rate. Moreover, the EOF rate was found to be proportional to both the applied voltage and the electrolyte concentration. Because of small electrokinetic radius of u-SNM arising from its ultrasmall pore size (ca. 2.3 nm in diameter), the EOF rate increased with increasing the electrolyte concentration and reached the maximum at a concentration of 0.4 M. This dependence was rationalized by the variations of both zeta potential and electrokinetic radius with the electrolyte concentration.