Using yttrium nitrate hexahydrate and calcium carbonate as yttrium and calcium sources, and urea as fuel, the Y2O3 coating CaO powder were prepared by low temperature self-spreading combustion synthesis (LCS) method. The CaO-Y2O3 composites were prepared by calcination, pressing, drying and sintering. The effects of the molar ratio of calcium to yttrium on the structure and properties of composites were investigated. The results show that the prepared Y2O3 coating CaO powder has good coating property. When the molar ratio of calcium to yttrium is 2∶1, the physical properties of the material are the best, the relative density is 96.56%, the apparent porosity is 1.32%, the compressive strength at room temperature is 270.0 MPa, the residual strength retention rate of the sample after 5 thermal shock cycles is 88.39%, and the hydration weight gain rate of the sample after 21 d in the atmospheric environment is 0.75%.