CuInS2 thin film used for photovoltaic applications was prepared by one-step electrodeposition. The films were annealed at different temperatures of 350, 400, 500 °C. Effects of annealing temperatures on the properties of the film were investigated by the way of X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-Vis-NIR Spectroscopy. The result shows that CuInS2 film with chalcopyrite structure can be successfully prepared by one-step electrodeposition. Annealing is effective in improving the crystallinity of the thin film. The temperature of 400°C is favorable to the grain growth of the film without the generation of impurity.