Abstract: In order to effectively monitor isobutylene gas, Cr₂O₃ and W-doped Cr₂O₃ (W/Cr₂O₃) films were successfully synthesized via aerosol-assisted chemical vapor deposition (AACVD) technique on the surface of alumina substrate. The microstructure, crystal structure, and elemental binding valence of Cr₂O₃ and W/Cr₂O₃ films were analyzed by SEM, TEM, XRD and XPS. The results show that Cr₂O₃ film is composed of nanoparticles with the particle size of about 50 nm, a thickness of about 20 μm, and its structure is relatively loose. However, the thin film obtained by W doping Cr₂O₃ has a compact structure, and the size of nanoparticles is about 15 nm, which is remarkably reduced due to the introduction of W into the Cr₂O₃ crystal lattice. Both Cr₂O₃ and W/Cr₂O₃ films have a single hexagonal crystalline structure. The gas sensitivity test results show that the sensitivity of the gas sensor based on W/Cr₂O₃ film towards 2×10^–5 isobutene increases from 1.11 to 3.55 compared with the Cr₂O₃ gas sensor at 400℃, and W/Cr₂O₃ gas sensor exhibits good stability, moisture resistance and gas selectivity.