The CZTS ink was prepared by a sonochemical method and properties of the CZTS thin films deposited by a spraying method were investigated. We used CuCl2, ZnCl2, SnCl2 and thiourea as precursor materials, 2-methoxyethanol as solvent, monoethanolamine as stabilizer, and NaCl as catalyst. X-ray diffraction (XRD) patterns from the CZTS films mainly exhibited the (112), (200), (220), and (312) planes of the kesterite structure. The grain size of CZTS films increased with increasing NaCl concentration. The optical band-gap of CZTS films decreased from 1.27eV to 1.08eV, and the absorption coefficient was increased, when the concentration of NaCl was increased. The elemental ratio of Cu:Zn:Sn:S in CZTS films was approximately 2:1:1:3.6, and the ratio of the films seldom changed at different synthesis conditions. These results demonstrate that the major role of NaCl is the enhancement of crystallinity and light absorption in CZTS films. The CZTS ink developed in this study has a promising potential for the formation of high quality CZTS thin films for photovoltaic devices.