Silicon oxide deposition on fine alumina powders by plasma-enhanced chemical vapor deposition (PECVD) at atmospheric pressure was carried out in a circulating fluidized bed reactor. To deposit silicon oxide on alumina powders, the organo-silicon source precursors (tetraethoxysilane (TEOS) and hexamethyldisiloxane (HMDSO)) and oxygen were used as the reactant gases while helium and argon were used as the dilute gases. The surface property of plasma-treated alumina powder varies from hydrophobic to hydrophilic in the surface composition with variation of the discharge power. In oxygen-containing atmospheres, chemical composition of the deposited film is more inorganic with increasing the discharge power and the flow ratio of O-2/precursor for both organo-silicon precursors.