The　geometry　and　electronic　structures　of　the　SnO2(110)　surface　have　been　investigated　by　using　the　first-principle　method.　Compared　to　an　ideal　surface,　the　five-fold　and　six-fold　Sn　atoms　at　the　top　layer　shift　inwards　and　outwards,　respectively.　For　the　surface　oxygen　atoms,　the　in-plane　oxygen　atoms　move　outwards,　while　the　displacement　of　bridged　oxygen　can　be　neglectable.　When　the　thickness　of　slab　is　smaller　than　3　nm,　the　oscillations　of　surface　energy　and　the　displacements　of　surface　atoms　as　a　function　of　the　number　of　layers　are　observed.　The　results　of　band　structure　calculations　show　that　the　energy　bands　mainly　originated　from　the　2p(y)/2p(z),　orbitals　of　the　bridged　oxygen　appear　in　the　bottom　of　the　band　gap　of　bulk.　Furthermore,　the　influences　of　the　surface　relaxation　on　the　electronic　properties　of　SnO2(110)　surface　are　also　discussed.