Abstract: Zirconia-mullite composite materials were synthesized by reaction sintering process, with fly ash, zircon and alumina micro powder as raw materials. The influence of sintering temperature on the linear shrinkage ratio, density, water absorbability, crushing resistance at normal temperature and thermal shock resistance of the synthesized materials were investigated. The phase composition and microstructure of the synthesized materials were characterized by XRD and SEM. The results indicated that the zirconia-mullite composite materials with high crushing resistance, thermal shock resistance and sinterability can be synthesized at 1600°C for 4h. It was found that the zirconia in the synthesized materials is mostly in particle shape with an average grain size about 5~10μm, and the particles are uniformly distributed in the mullite matrix.