Bimetallic　metal-organic　frameworks　(BMOFs)　have　shown　a　superior　oxygen　evolution　reaction　(OER)　performance,　attributed　to　the　synergistic　effects　of　dual　metal　sites.　However,　the　significant　role　of　these　dual-metal　synergies　in　the　OER　is　not　yet　fully　understood.　In　this　study,　we　employed　density　functional　theory　to　systematically　investigate　the　OER　performance　of　NiAl-　and　NiFe-based　BMOFs　by　examining　all　possible　spin　states　of　each　intermediate　across　diverse　external　potentials　and　pH　environments.　We　found　that　the　spin　state　featuring　a　shallow　hole　trap　state　and　Ni　ions　with　a　higher　oxidation　state　serve　as　strong　oxidizing　agents,　promoting　the　OER.　An　external　potential-induced　spin　crossover　was　observed　in　each　intermediate,　resulting　in　significant　changes　in　the　overall　reaction　and　activation　energies　due　to　altered　energy　levels.　Combining　the　constant　potential　method　and　the　electrochemical　nudged　elastic　band　method,　we　mapped　the　minimum　free　energy　barriers　of　the　OER　under　varied　external　potential　and　pH　by　considering　the　spin　crossover　effect　for　both　NiAl　and　NiFe　BMOFs.　The　results　showed　that　NiFe　exhibits　better　OER　thermodynamics　and　kinetics,　which　is　in　good　agreement　with　experimentally　measured　OER　polarization　curves　and　Tafel　plots.　Moreover,　we　found　that　the　improved　OER　kinetics　of　NiFe　not　only　is　attributed　to　lower　barriers　but　also　is　a　result　of　improved　electrical　conductivity　arising　from　the　synergistic　effects　of　Ni-Fe　dual-metal　sites.　Specifically,　replacing　the　second　metal　Al　with　Fe　leads　to　two　significant　outcomes:　a　reduction　in　both　the　band　gap　and　the　effective　hole　mass　compared　to　NiAl,　and　the　initiation　of　super-　and　double-exchange　interactions　within　the　Ni-F-Fe　chain,　thereby　enhancing　electron　transfer　and　hopping　and　leading　to　the　improved　OER　kinetics.　©　2024　The　Authors.　Published　by　American　Chemical　Society.