Growth of ZnO epitaxial films have been carried out on (0001) sapphire substrates by RF magnetron sputtering. The single crystalline ZnO films of the thickness about 400-500 mm were grown successfully. At the various substrate temperatures of 200～$600^{circ}C$, the growth behavior and optical properties of the epitaxial films have been characterized. As-grown ZnO films were annealed at the temperatures of 400, 600 and $800^{circ}C$ respectively in order to characterize the optical properties. The carrier concentration of ZnO films annealed at the temperature of $600^{circ}C$ was measured $2.6${ imes}$10^{16} extrm{cm}^{-3}$</TEX> by Hall measurements.