Sb2Se3−xSx　is　considered　a　promising　absorber　material　for　solar　cell　applications　because　of　its　tunable　band　gap.　However,　theoretical　research　on　Sb2Se3−xSx　is　still　limited.　In　this　research,　the　crystal　structure,　electronic　structure　and　photoelectric　properties　of　Sb2Se3−xSx　(x=0,　0.125,　0.25,　0.5,　0.75)　were　determined　using　first-principles　calculations　based　on　density　functional　theory.　The　band　gap　is　affected　by　the　structural　distortion　and　covalence　of　Sb2Se3−xSx　with　increasing　S　concentration.　From　x=0　to　x=0.75,　the　covalence　of　Sb2Se3−xSx　gradually　increases.　While　for　x=0.125　and　x=0.25,　the　structural　distortion　are　more　severe　than　the　others.　Combining　with　the　affects　of　both,　the　band　gap　decreases　first　and　then　increases　with　increasing　S　concentration.　By　calculating　the　carrier　effective　masses　and　optical　characteristics　of　Sb2Se3−xSx,　it　can　be　found　that　Sb2Se3−xSx　(x=0.5)　shows　the　optimized　photoelectric　properties.　The　results　provide　some　guidance　for　the　further　development　of　Sb2Se3−xSx　solar　cells　by　adjusting　band　gap.　©　2019　Elsevier　Inc.