γ-Fe₂O₃ thin films on Al₂O₃ substrate were prepared by the oxidation of Fe₃O₄ thin films processed by PECVD(Plasma-Enhanced Chemical Vapor Deposition) technique. The phase transformation of γ-Fe₂O₃ thin films was mainly controlled by the substrate temperature and oxidation process of Fe₃O₄ phase. Fe₃O₄ phase was obtained at the deposition temperature of 200∼300℃. Fe₃O₄ phase could be transformed into γ-Fe₂O₃ phase under controlled oxidation at 280∼300℃. Fe₃O₄ and γ-Fe₂O₃ obtained by oxidation of Fe₃O₄ phase had the same spinel structure and were coexisted. The oxidized γ-Fe₂O₃ thin film on Al₂O₃ substrate showed a porous island structure.