Low cost and environment friendly Cu2ZnSnS4 (CZTS) is the best candidate to replace CuInxGa1-xSe2 (CIGS) which owns noble and toxic metal for thin film solar cells. Electrodeposition technique is a low cost method where vacuum equipment and target materials are not required. A simpler fabrication method is co-electrodeposition of Cu-Zn-Sn (CZT) alloy on fluorine-doped tin oxide (FTO) in aqueous solution. In this paper, CZTS thin films were successfully prepared by sulfurization of electrodeposited CZT alloy precursors at 550oC in protective argon gas. The CZT precursors were electrodeposited on FTO via a three-electrode system in which FTO is used as working electrode, platinum (Pt) mesh and Ag/AgCl as counter and reference electrodes. The electrolyte contains CuSO4, ZnSO4, SnSO4, complexing agent-Triethanolamine (TEA) and sodium citrate. The precursors were sulfurized by sulfur vapor at 550 ℃ in protective argon gas and then CZTS films were obtained. The structural, morphological, compositionaland optical properties of CZTS films have been characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), UV-vis spectroscopy and photoelectrochemical measurement (PEC). XRD and Raman spectroscopy have confirmed the kesterite structure of CZTS films sulfurized at 550 ℃. One major peak at 342 cm-1 and two second strong peaks at 289 and 370 cm-1 are observed in the Raman spectra, which agree with those reported from kesterite CZTS. SEM shows chemical composition of optimum CZTS film is near that of stoichiometric CZTS. The ratios of Cu/(Zn+Sn) and S/(Zn+Sn+Cu) in CZTS film are 052 and 101, respectively, which indicates that the content of S in “copper poor” CZTS film is very suitable. The photocurrent of the “copper-poor” CZTS film was measured by PEC. PEC results confirm that light current is produced by FTO/CZTS under front/back irradiation, and the photocurrent flows in the same direction in both cases. The band gap of CZTS is 145 eV. It is shown that high-quality CZTS thin films have been prepared via above analysis.