Due to its high melting point, low thermal conductivity, and good phase stability at high-temperature, rare earth zirconates material (A2B2O7) will be one of the candidate materials used for the thermal barrier coating. At high temperature, the chemical stability between rare earth zirconates and TGO layer (mainly Al2O3) affects much the performance of coating, so the study of the chemical stability is of great significance. In this paper, (Sm1-xLax)2Zr2O7(x=0, 1) were prepared by the co-precipitation method and the chemical stability between (Sm1-xLax)2Zr2O7(x=0, 1) and Al2O3 was investigated at the temperature of 1 200 ° ?C,1 300 ° ?C, 1 400 ° ?C, 1 500 ° ?C, 1 600 ° ?C respectively for 8 h¡¢24 h. The microstructures were analyzed by scanning electron microscope (SEM) and the crystallographic phases were determined by X-ray diffraction (XRD). The results showed that the chemical reaction occurred between Sm2Zr2O7 and Al2O3 above 1 200 ° ?C producing SmAlO3. With the heating temperature increased, the content of SmAlO3 increased. The chemical reaction between La2Zr2O7 and Al2O3 began at 1 200 ° ?C producing LaAlO3 and ZrO2. LaAl11O18 appeared at 1 300 ° ?C. As the increase of heating temperature, the content of LaAlO3 and ZrO2 with tetragonal phase reduced gradually in the heated samples, and the content of LaAl11O18 and ZrO2 with monoclinic phase increased gradually in the heated samples. With the increase of heating temperature, the doping amount decreases in ZrO2 with tetragonal phase, the structure of ZrO2 with tetragonal phase tend to be more complete. So ZrO2 with tetragonal phase transformed to ZrO2 with monoclinic phase in cooling process easily, which leads to the increase of ZrO2 with monoclinic phase in the heated samples. As the time of heating temperature prolonged, the kinds of reaction products didn ?t change, but the amount of reaction products increased.