La2(Zr0.7Ce0.3)2O7 (LZ7C3)ceramic was synthesized by solid state reaction with La2O3,ZrO2 and CeO2 as starting materials.The synthesis kinetics,phase structure,mass loss and microstructure were studied by thermo gravimetric-different thermal analyzer (TG-DTA),X-ray difference (XRD) and scanning electron microscopy (SEM).The thermal conductivity and thermal expansion coefficient were measured by laser-flash method and pushing-rod method,respectively.XRD results showed that LZ7C3 was a mixture of La2Zr2O7 (LZ,pyrochlore) and La2Ce2O7 (LC,fluorite).The lowest synthesis temperature and time of LZ7C3 were 1400 ℃ and 5 h.There were no peaks of La2O3 when the powder granularity was about 0.82 μm in the synthesis process.The atom ratio La∶Zr∶Ce of prepared LZ7C3 powder was very close to 10∶7∶3 which was the theory value of LZ7C3.The thermal conductivity of LZ7C3 decreased gradually with the temperature increased up to 1200 ℃,and was located within 0.79 to 1.02 W/(m·K),which was almost 50％ lower than that of LZ,whereas its thermal expansion coefficient was larger and the value was 11.6× 10-6 K-1.