In order to develop novel ceramic material for thermal barrier coatings, the (Sm0.5Gd0.2 Nd0.3)2(Hf0.3Ce0.7)2O7 composite oxides were synthesized by high temperature sintering method in this paper. Its lattice-type was analyzed by XRD, the microstructure was analyzed by SEM, thermal expansion property was tested by thermal expansion instrument, and thermal diffusivity was measured by laser thermal laser conductor-meter. Results show that the pure (Sm0.5Gd0.2Nd0.3)2(Hf0.3Ce0.7)2O7 with single fluorite lattice was synthesized. The microstructure is very dense, and interfaces between boundaries are very clean, no other phases can be found. Owing to the complex element constituent and high atomic weight, its thermal conductivity is lower than those of 7YSZ and Sm2Ce2O7. The relative low thermal expansion coefficient of (Sm0.5Gd0.2Nd0.3)2(Hf0.3Ce0.7)2O7 can be contributed to the lower ionic radius of cations at B sites, while the thermal expansion coefficient meets to the requirement for thermal barrier coatings.