In this paper, Cd1-xZnxS thin films were prepared by chemical bath deposition (CBD), and the effects of different zinc doping content on the morphological structure and optical properties of Cd1-xZnxS buffer layers are systematically discussed. The experimental results show that in the deposition process of different substrates, the crystal structure of the film is all hexagonal, and when the concentration of zinc sulfate (ZnSO4) precursor is varied from 0 to 0.025 M, the films are uniform and dense. With the increase of zinc content, the X-ray diffraction (XRD) peak of the films shifted behind that of CdS film (002). It showed 70% to 90% transmittance in the visible region and the optical band gap increased gradually. The band gap value of the films obtained ranged from 2.43 eV to 3.01 eV. It shows the potential feasibility of its application to photovoltaic devices.