Abstract: Nanostructured ZrO2 functional gradient thermal barrier coating was prepared by air plasma spraying technology. The porosity,size and shape of the pores in the ceramic layer,intermediate layer and interface between ceramic layer and intermediate layer were analyzed by quantitative analysis technology. The results show that the pores possessed the same microstructure characteristics in the ceramic layer,intermediate layer and interface. The cumulative probability of the porosity,the pore size and the pore shape showed similar distribution in different layers. The greatest porosity appeared in the interface between ceramic layer and intermediate layer,being about 6.87%. Most of the pores size in the coating was smaller than 1 μm(about 65%),and showed equiaxial shape (with the content of 70%-73%).