Normally, CdS film is used as the buffer layer in the fabrication of copper indium gallium selenide solar cells. These solar cells can reach an efficiency of 10.3% when produced by a non-vacuum process. However, this is a very toxic process. In this study, we propose using a nontoxic zinc sulfide (ZnS) buffer layer which is deposited by chemical bath deposition. It took only 15 minutes to reach a ZnS thickness of 50nm and the transmittance of the finished device was higher than 80%. The back contact of the Mo layer sheet resistivity is 0.22 (Ω/square). The precursor solution for the cell fabrication was prepared from anhydrous hydrazine. The film was then deposited by spraying and finally heated rapidly to 520 without external selenization.