SnO2-In2O3 hierarchical microspheres were prepared by the hydrothcrmal and solvothermal method.The morphology,phase crystallinity of the obtained SnO2-In2O3 were measured by X-ray diffraction(XRD),scan electron microscopy(SEM),respectively.A room temperature ozone sensor based on SnO2-In2O3 hierarchical microsphcres was fabricated and investigated.The gas sensing properties of the sensor using SnO2-In2O3 strongly depended on the proportion of SnO2 and In2O3.The sensitivity and response/recovery speed were greatly enhanced by UV illumination.A gas sensing mechanism related to oxygen defect was suggested.