Zirconia filing, deposited by PVD both at 300℃ and the room temperature, show crystalline inhomogeneity after a certain thickness: the tetr, phase exists on the eubstrate side and the monocline on the air side. It has been discussed that the cause of tetr. phase can be stable at room temperature in zirconia films. And from the concept of growing con-test, the reuson of resulting in the columnar miorostruoture and optical inhomogeneity of thin films is analyzed.