Abstract: Metal oxide semiconductor gas sensors have the advantages of good stability, low cost, high sensitivity, etc., and are widely used to monitor volatile organic compounds, but there are still problems such as unsatisfactory reproducibility of the preparation of sensitive materials, high optimal operating temperature, and poor moisture resistance. In this paper, a CeO₂/CuO composite film was successfully prepared by magnetron sputtering process with planar electrode as the substrate, and a gas sensor was constructed based on the composite film. The surface microstructure and chemical composition of CeO₂/CuO composite films were analysed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), and the gas-sensitive and moisture-resistant properties of CeO₂/CuO composite film gas sensors were further investigated. The results showed that the CeO₂/CuO composite thin-film gas sensor has a low optimum operating temperature (160 ºC), good selectivity, wide monitoring range and high sensitivity to triethylamine. In addition, the moisture resistance of the gas sensor was significantly improved with the increase of CeO₂ content.