In　this　work,　mirror-like　Co9S8　nanosheets　in-situ　grown　on　indium　tin　oxide　(ITO)　glass　substrate　have　been　synthesized　through　a　facile　hydrothermal　method　and　used　as　a　novel　Ptfree　counter　electrode　(CE)　for　dye-sensitized　solar　cells.　Based　on　mirror　effect　of　the　Co9S8　CE,　incident　light　has　been　efficiently　utilization.　As　a　result,　the　cell　using　Co9S8　nanosheets　CE　achieved　a　power　conversion　efficiency　of　9.01%,　which　is　higher　than　that　of　Pt　CE.　This　could　be　contributed　to　the　fact　that　mirror-like　Co9S8　nanosheets　exhibited　an　excellent　catalytic　activity　for　the　reduction　of　I-3(-)/I-.