In order to improve the oxidation resistance and ablation resistance of ZrB2-SiC ultra-high temperature ceramics (UHTCs), Y2O3 particles were introduced during the fabrication process of the ZrB2 based UHTCs. The oxidation-resistance and ablation-resistance of ZrB2-SiC-Y2O3 UHTCs were investigated using oxyacetylene torch test. The microstructures and phases of ZrB2-SiC-Y2O3 before and after ablation were studied by SEM and XRD. No cracks are found on the ablated surface during the process of heating and cooling, indicating that ZrB2-SiC-Y2O3 UHTCs have good thermal shock resistance. Microstructure analysis shows that the oxidation layer is composed of 4 layers and there is no obvious exfoliation between the oxidation layer and the substrate layer. The results show that high temperature stable phase t-ZrO2 in the oxidation product can be kept at low temperature by the addition of Y2O3, thus reducing the volume expansion owing to transformation and improving coherent properties of oxidation layers