Sb2Se3 is a promising photovoltaic material having advantages of suitable bandgap, strong light absorption, simple phase, nontoxicity, and earth-abundant constituents. Different buffer layers were used to fabricate Sb2Se3 solar cells. However, the efficiency of SnO2/Sb2Se3 solar cells was limited by the crystallinity and surface roughness of the SnO2 film. In this study, lanthanum was doped on the SnO2 film to increase crystallinity and impart surface uniformity. Moreover, the influence of La doping on the solar cell performance was investigated in detail. An average efficiency of 3.25% for the La-doped SnO2/Sb2Se3 solar cells was obtained.