Abstract: LaNiO₃ thin films were deposited on K9 substrates at substrate temperature of 350℃by rf-magnetron sputtering system. The optical characteristics, electric properties and microstructure of thefilms were investigated. The films are found to be amorphous when thickness is less than 100nm, andhighly（100）-orientated when thickness is over 150nm. The results also show that optical and electricproperties of films with amorphous structure are similar to those of dielectrics, while films with crystalstructure provide metallic properties. An explanation for these results is that an amorphous layer willbe formed at the initial stage of film growth.