The composite coatings were prepared on aluminum alloy by anodizing and chemical conversion method. The coatings consisted of a anodic oxide coating and a rare earth conversion coating. The surface morphology and composition of the composite coatings were analyzed by scanning electron microscopy (SEM) and energy dispersive X-rays (EDX). The electrochemical properties of the different samples were researched by Potentiodynamic polarisation and electrochemical impedance spectroscopy in a 3.5-wt.% NaCl solution. The results showed that corrosion current density of the sample with composite coatings was 3.611×10-9 A·cm-2, impedance was 6.107×105 Ω·cm-2. The composite coatings had better corrosion resistance than the sample with anodic oxide film and the aluminum alloy substrate.