The　stoichiometric　tritungsten　oxide　Cluster　(W3O9)　deposited　on　the　TiO2(110)　Surface　has　been　investigated　using　first-principles　density　functional　theory　calculations.　Various　possible　configurations　mainly　derived　from　molecular　dynamics　simulations　have　been　considered.　On　the　basis　of　the　comparisons　of　thermodynamic　stability　and　STM　images,　two　isoenergetic　structures　with　chirality　relationship　between　the　geometries　of　W3O9　Clusters　can　be　tentatively　assigned　to　be　the　most　likely　configurations　under　the　experimental　conditions,　in　which　five　new　bonds　including　three　Ti-O　and　two　W-O　bonds　are　formed　at　the　interface.　Due　to　the　loss　of　three　W=O　groups,　the　low　chemical　reactivity　of　the　W3O9　Cluster　can　be　expected.　After　deposition　of　W3O9,　the　TiO2(110)　Surface　still　retains　the　semiconducting　character　and　the　charge　transfer　Occurring　between　the　Cluster　and　the　substrate　is　small.　The　variation　of　surface　dipole　moment　is　sensitive　to　the　orientation　of　the　six-membered　ring　structure　of　W3O9.　In　addition,　our　results　indicate　that　the　properties　of　the　TiO2(110)　surface　may　be　adjusted　by　deposition　of　nonstoichiometric　tungsten　oxides.