ZrO2 sols were prepared with hydrothermal synthesis method. The ZrO2films were characterized or examined by many kinds of instruments. With different content of zirconium oxychloride octahydrate, the particle sizes of ZrO2 sols are different from 3nm to 25nm. And 1-on-1 laser-induced damage threshold tests on ZrO2 films were carried out with a Q–switched Nd-YAG high power laser at 1064 nm. The experimental results showed that the ZrO2 sols is suitable for preparing ZrO2thin film and the refractive index and thickness of this thin films achieve our requirement.