In this paper, CdxZn1-xS thin films were deposited on glass substrates by chemical bath deposition (CBD), and the effects of different concentrations of ammonia water on the morphology, structure and optical properties of the films were studied. CdxZn1-xS thin films have hexagonal crystal structure, the transmittance is above 75% in the visible range, and the optical band gap is between 2.6 eV and 2.9 eV. The influence of the experimental group of deposited thin films on the performance parameters of the Cu(In,Ga)Se2 (CIGS) battery was studied by simulation with solar cell capacitance simulator (SCAPS-1D) software, and the cell efficiency reached 22.42%. It is introduced that the buffer layer prepared in this experiment is feasible in CIGS solar cells.