Abstract: A French commercial available alpha-alumina tubular membrane was modified with nano zinc oxide prepared by homogeneous precipitation process using urea and zinc nitrate as raw materials. The modified membrane was characterized with SEM、FTIR、XRD and the influences of the modification on the streaming potential of the alumina membrane and electrophoretic mobility of alumina grains were investigated. The results showed that after modification there was a nano zinc oxide coating with grain size of less than 30nm formed on the alumina grains ' surface and the streaming potential of the modified membrane decreased, so as for the electrophoretic mobility of the alumina grains. The stabilized permeability of the modified membrane had an increase of 156;. It is pointed that this great increase of permeability is due to the increase of membrane's effective pore radius and the decrease of water viscusity near pore walls of membranes.