The hydrophilic polymer-ceramic composite membranes were prepared by grafting polyacrylic acid onto activated surfaces of alumina substrates, such as homogeneous alumina membranes and asymmetric alumina membranes with different pore sizes. It is shown from the results of characterization including analysis of IR, XPS, SEM, and the water contact angle of the surface that the PAA-Al2O3 composite membrane is successfully prepared. The permeation flux experiments of pure ethanol or pure water and the dewatering separation tests of the 95wt% ethanol were done with the composite membranes prepared. And it is shown from the experimental data that most suitable ceramic membrane substrate for a PAA-Al2O3 composite membrane is the homogeneous alumina substrate with pore sizes of 2-3 μm, and the separation factor of the PAA-Al2O3 composite membrane made with it is 139.33 and the permeation flux is 0.61 kg•m－2•h－1. The high separation efficiency and great membrane flux are achieved by using the PAA-Al2O3 composite membrane.