Coordinatively　unsaturated　metal　(CUM)　sites　of　metal　organic　frameworks　(MOFs)　play　an　important　role　in　water　adsorption　and　its　effects　on　CO2　capture.　To　explore　the　trends　among　various　metal　identities　toward　water,　M-HKUST-1　analogous　to　HKUST-1　based　on　different　metal　sites　M　(M　=　Zn,　Co,　Ni,　and　Mg)　are　chosen　as　model　frameworks　and　their　water　effects　on　CO2　capture　are　evaluated.　Our　results　demonstrate　that　Mg-based　framework　shows　diverse　effects　by　water　coordination　from　Zn-,　Co-,　and　Ni-based　frameworks.　Water　coordination　lowers　CO2　uptake　dramatically　in　Mg-HKUST-1　whereas　improves　CO2　adsorption　in　Zn-,　Co-,　and　Ni-HKUST-1　at　most　of　the　pressure　ranges　we　studied.　The　detailed　evaluation　of　interaction　energy　indicates　that　with　the　increased　loading　of　CO2　molecules　both　the　weaker　interactions　between　CO2　and　the　framework　and　CO2-CO2　contribute　to　the　lower　CO2　uptakes　of　the　hydrated　Mg-HKUST-1.　These　findings　could　benefit　CUMs　screening　in　MOFs＇　design　for　CO2　capture　and　other　applications.