Abstract: The ZrB2 coated with Al2O3-Y2O3 composite powders were obtained by co-precipitation method.The composite ceramics were prepared by spark plasma sintering (SPS)technique.Oxidation tests of the composite ceramics with different YAG(yttrim aluminum garnet)and Al2O3 contents were performed.The effects of YAG and Al2O3 on oxidation resistance of the ZrB2 ceramics were analyzed by using SEM,XRD and EPMA.The results show that the oxide layer thickness of ZrB2 ceramics added with YAG Al2O3 decreased compared to pure ZrB2 ceramics under the same oxidized conditions.YAG and Al2O3 could improve the oxidation resistance of ZrB2 ceramics.The more the Al2O3 content,the thinner the oxide layer thickness.Under high temperature condition the oxide layers on the composite ceramics were composed of ZrO2,B2O3 and Al18B4O33 phase.The more the Al2O3 content,the more the Al18B4O33 phase.