High temperature gas turbine sealing is an important issue for increasing the thermal efficiency of gas turbine. In this purpose, layered structured LaPO4 has been selected as the soft phase to add into the commercialized thermal barrier coating material 7 wt% yttria stabilized zirconia (7YSZ). The consequent thermal conductivities and mechanical properties versus the content of LaPO4 have been researched systemically in this paper. Phase composition and microstructure of the high-temperature sintered LaPO4/7YSZ composites were characterized. The thermal conductivity decreases significantly due to the second phase effects and the interface thermal resistance was also strongly involved according to the composite model. The hardness decreased by composed LaPO4 phase so that to reduce attrition of the vanes at high temperature. The slight increase of fracture toughness and bending strength in the results were also favored in operation. The experimental results demonstrate that the LaPO4/7YSZ composite will be an excellent candidate abradable sealing material for high temperature gas turbine.