Abstract: La₂O₃-Y₂O₃-ZrO₂(YSZ) composite ceramic powders with various La₂O₃ doping contents were prepared by chemical co-precipitation calcination method. High temperature phase stability, sintering resistance and thermo-physical properties of this composite ceramic powder were studied and also compared with those of the traditional YSZ ceramic powder in order to explore the possibility of La₂O₃-YSZ for thermal barrier coating material application. The crystal structure and phase composition of the ceramic powders were analyzed by XRD. The effect of La₂O₃ doping content on the high temperature phase stability of YSZ was investigated. SEM was used to analyze the microstructure of the sintered ceramics to investigate the effect of La₂O₃ doping on the sintering resistance of YSZ. Thermal diffusivity was tested by laser flash method and the thermal conductivity of material was obtained by calculation. The results indicate that YSZ and various La₂O₃ doping La₂O₃-YSZ are all composed of single non-equilibrium tetragonal phase ZrO₂ (t'- ZrO₂ ). After 100 h heat treatment at 1 400 ℃, the t'-ZrO₂ in YSZ has completely transformed to cubic phase ZrO₂ (c-ZrO₂) and monoclinic phase ZrO₂ (m-ZrO₂). In the 0.4mol%-1.4mol% La₂O₃ doping range, La₂O₃-YSZ exhibits good phase stability than that of YSZ. YSZ doped by 1.0mol% La₂O₃ (1.0mol% La₂O₃-YSZ) does not generate m-ZrO₂ after thermal treatment, showing good high temperature phase stability. In addition, 1.0mol% La₂O₃-YSZ has better sintering resistance and lower thermal conductivity in comparison with YSZ. In the temperature range from room temperature to 700 ℃, the thermal conductivity of 1.0mol% La₂O₃-YSZ is 1.90-2.17 W/(m·K) which is obviously lower than that of YSZ (2.13-2.33 W/(m·K)).