Thermal barrier coatings (TBCs) are mostly applied to hot components of advanced turbine engines to insulate the components from hot gas. The effect of sintering on thermal conductivity and thermal barrier effects of conventional plasma sprayed and nanostructured yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs) are investigated. Remarkable increase in thermal conductivity occurs to both typical coatings after heat treatment. The change of porosity is just the opposite. The grain size of the nanostructured zirconia coating increases more drastically with annealing time compared to that of the conventional plasma sprayed coating, which indicates that coating sintering makes more contributions to the thermal conductivity of the nanostructured coating than that of the conventional coating. Thermal barrier effect tests using temperature difference technique are performed on both coatings. The thermal barrier effects decrease with the increase of thermal conductivity after heat treatment and the decline seems more drastic in low thermal conductivity range. The decline in thermal barrier effects is about 80 °C for nanostructured coating after 100 h heat treatment, while the conventional coating reduces by less than 60 °C compared to the as-sprayed coating. Thermal barrier coatings (TBCs) are mostly applied to hot components of hot gas. The effect of sintering on thermal conductivity and thermal barrier effects of conventional plasma sprayed and nanostructured yttria stabilized zirconia (YSZ) thermal barrier coatings The change of porosity is just the opposite. The grain size of the nanostructured zirconia coating increases more drastically with annealing time compared to that of the of the conventional plasma (TBCs) are investigated. sprayed coating, which indicates that coating singeing more than to thermal conductivity of the nanostructured coating than that of the conventional coating. Thermal barrier effect tests using temperature difference techniques are performed on both coatings. conductivity after he at treatment and the decline seems more drastic in low thermal conductivity range. The decline in thermal barrier effects is about 80 ° C for nanostructured coating after 100 h heat treatment, while the conventional coating reduces by less than 60 ° C compared to the as- sprayed coating.