The hollow porous NiO/SnO₂ composite nanofibers were prepared by electrospinning method, then the carbon nanotubes (CNTs) were decorated on the surface of the composite fibers and this material marked as CNTs/NiO/SnO₂. On this basis, a gas sensor device was prepared. The thermal decomposition temperature of the composites was determined by TGA, and the heat treatment process was obtained. The morphology, structure, size and surface composition of the composites were characterized by SEM, XRD, TEM and XPS. The test results of the gas sensors based on the composites showed that the gas sensor prepared by CNTs NiO/SnO₂ composite nanomaterial reduces the optimum working temperature in detecting acetone gas, which was 160°C, and the composite nanomaterial also improved the detection sensitivity. The gas sensors based CNTs/NiO/SnO₂ had a good response to 50 ppm acetone, reaching at 25.25, responded quickly to the detection of acetone (~8.2 s) and recovery performance (~10.5 s), while also showing good stability in the 30 day long-term stability test. In this research, the potential value of NiO/SnO₂ composites with decorative CNTs in the detection of acetone was proved. At the same time, the mechanism of the improvement of detection performance of CNTs and hollow porous structure NiO/SnO₂ was discussed.