There are many articles on gas sensor research[1–4],Measuring the acetone content of exhaled breath can reflect changes in blood sugar in the body. Therefore, it is of great value to develop gas sensitive materials for detecting acetone gas effectively. In this paper, by adding SnO2 to In2O3. composite In2O3/SnO2 microspheres were prepared. Using XRD, SEM, TEM, XPS, PL and UV technology, the microstructure morphology and optical properties of In2O3/SnO2 were measured. The experimental results showed that the composite retained the advantages of In2O3 and SnO2 optimized the properties of the composite effectively, and reduced the photoluminescence intensity. The gas sensitive properties of In2O3/SnO2 composite samples were tested. The test results showed that compared with pure In2O3 samples, the optimal working temperature of In2O3/SnO2 was reduced by 30 °C to 250 °C. The response value to acetone gas is increased to about 35. In addition, In2O3/SnO2 sensors also achieve good selectivity excellent moisture resistance. long-term stability. These results show that the heterojunction of SnO2 and In2O3 can be used as an excellent sensor for detecting acetone gas.