Cu2SnSe3 (CTSe) thin films were fabricated by coevaporation on soda-tune glass substrates at the substrate temperature of 300 °C under rations Co Sd supply ratios. From X-ray diffraction ( XRD) analyses, diffraction peaks of CTSe with a cubic sphalerite structure were observed in all CTSe thin films. In addition, SnSe and SnSe2 phases were also detected in Sn-ricb CTSe thin films. On the other bands, in Cu-rich CTSe thin films, a Cu2Se secondary phase was observed by Raman scattering measurements. Surface and cross-sectional observations revealed that these secondary phases were mostly segregated on the] surface of the thin films. The electrical properties of CTSe thin films changed strongly by Co. Sn ratios in the thin films.