Using　the　first-principles　calculation,　we　explore　the　interfacial　characteristics　of　ZnO　monolayer　on　the　Cu(111)　surface　with　and　without　oxygen　vacancy.　It　is　found　that　electrons　transfer　from　the　Cu　substrate　towards　the　ZnO　monolayer　and　the　different　position　of　O　atoms　relative　to　the　Cu　surface　determine　the　interfacial　interaction　and　then　turn　a　flat　graphitic　ZnO　monolayer　into　an　asymmetrical　dumpling　structure.　The　oxygen　vacancy　is　not　only　the　result　of　substrate　stabilisation　effect　but　also　strengthen　the　interfacial　interaction　to　make　charge　transfer　mechanism　and　dumpling　effect　dominant　to　the　compression　effect,　thus　resulting　in　an　overall　increase　of　Cu　work　function　and　the　decreasing　of　potential　step.　[GRAPHICS]　.