Cu2ZnSn(S, Se)4 films were fabricated through post-selenization of Cu-Zn-Sn-S precursors co-electroplated by varied Na2S2O3·5H2O concentrations. The property of obtained films before and after selenization shows a close dependence on the concentration of Na2S2O3·5H2O. Only the film grown by 5 mM of Na2S2O3·5H2O shows a uniform surface with faceted grains, a Zn-poor composition, a single phased Cu2ZnSn(S, Se)4 structure and a 1.11 eV band gap evidencing by SEM, EDS, XRD, Raman and transmittance spectra. More than 5 mM of Na2S2O3·5H2O additive to the electrolyte yielded the films with rougher morphology and the presence of SnSex. Less than 5 mM of Na2S2O3·5H2O additive to the electrolyte resulted in the films with highly Zn-poor content and the primary formation of Cu2SnSe3.