Different doped polyaniline films were prepared by galvanostatic method at low current density. The adsorption properties of different doped polyaniline films were studied using cyclic voltammetry, and the surface morphology was analyzed using scan electron microscopy. The results indicate that three different doped polyaniline films(PAn) have different adsorption properties to ethanol molecules. Compared with KCl/PAn, PAn and ZnO/PAn have better adsorption capabilities. The adsorption properties are relative with the structure of the polyaniline films.