The nanostructured and conventional zirconia coatings were fabricated by an atmosphere plasma spraying technique. The microstructure of the as-sprayed zirconia coatings was analyzed. The results show that the nanostructured zirconia coating is a typical lamellar structure composed of columnar grain about 100nm in diameter. In the nanostructured zirconia coating, the pore is fine and of homogeneous distribution, and there exist a large quantity of small microcracks. The nanostructured zirconia coating possesses better thermal shock resistance than the conventional zirconia coating. ( From : No.1, 2006 Journal of Inorganic Materials )