The composite tubular membranes were prepared by applying suspensions of zirconia particles to form separation top-layers on two different porous alpha-alumina supports and heating the coated supports to partly sinter the particles of top-layers. The conditions of synthesizing the ZrO2/alpha-Al2O3 membranes were investigated systematically. The mean pore diameter of zirconia membrane was about 0.2 mu m by gas bubble pressure method, and the pure water flux was about 400 and 1500 1/(m(2) h bar) for ZrO2 membrane on symmetric and asymmetric Al2O3 support, respectively. Zirconia membrane and three different alumina membranes were applied to separate oil-water emulsion obtained from steelworks to evaluate the permeability and separation characteristics, the ZrO2/alpha-Al2O3 MF membrane in this work was the preferred membrane.