The　oxygen　evolution　reaction　(OER)　performance　of　NiCo　LDH　electrocatalysts　can　be　improved　through　fluorine　doping.　The　roles　of　Ni　and　Co　active　sites　in　such　catalysts　remain　ambiguous　and　controversial.　In　addressing　the　issue,　this　study　draws　upon　the　molecular　orbital　theory　and　proposes　the　active　center　competitive　mechanism　between　Ni　and　Co.　The　doped　F-atoms　can　directly　impact　the　valence　state　of　metal　atoms　or　exert　an　indirect　influence　through　the　dehydrogenation,　thereby　modulating　the　active　center.　As　the　F-atoms　are　progressively　aggregate,　the　e(g)　orbitals　of　Ni　and　Co　transition　from　e(g)(2)　to　e(g)(1),　and　subsequently　to　e(g)(0).　The　corresponding　valence　state　elevates　from　+2　to　+3,　and　then　to　+4,　signifying　an　initial　increase　followed　by　a　subsequent　decrease　in　the　electrocatalytic　performance.　Furthermore,　a　series　of　F-NiCo　LDH　catalysts　are　synthesized　to　verify　the　e(g)　orbital　occupancy　analysis,　and　the　catalytic　OER　overpotentials　are　303,　243,　240,　and　246　mV　at　the　current　density　of　10　mA　cm(-2),　respectively,　which　coincides　well　with　the　theoretical　prediction.　This　investigation　not　only　provides　novel　mechanistic　insights　into　the　transition　and　competition　of　Ni　and　Co　in　F-NiCo　LDH　catalysts　but　also　establishes　a　foundation　for　the　design　of　high-performance　catalysts.