Abstract: Cd2SnO4 was prepared by hydrothermal calcination, and a series of g-C3N4- Cd2SnO4 composites with different mass ratios were prepared by sonication mixing method. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and other methods. The gas-sensing properties of g-C3N4-Cd2SnO4 composites in different proportions were studied. The results show that when the addition amount of g-C3N4 was 2.5 wt% (mass fraction), the sensitivity of g-C3N4-Cd2SnO4 composites to gas was the highest, and the response of 100 μL/L isopropanol gas was up to 117 at the optimal working temperature of 170°C, which was 78 times higher than that of pure Cd2SnO4 with a sensitivity of 1.4, and the low detection limit was 0.1 μL/L.