We report the synthesis of nitridation-induced NiFe-MOF through post-synthetic functionalization of ter-minal ligand in NiFe-MOF nanosheet.We directly identify the key factor of amino ligand in N-NiFe-MOF for boosting the OER performance through combining single X-ray crystallographic characterization and in-situ Raman tracking,as well as ex-situ spectroscopy analysis.Density functional theory (DFT) calcula-tions and experimental results indicate irreversible phase reconstruction from amino ligand oxidation prior to OER could lead to the optimized △G·O,resulting in the remarkable OER performance with an overpotential of 258 mV to obtain the current density of 100 mA cm-2 in 1.0 M KOH solution.Our work will provide new strategy for rational designing advanced MOF-based OER electrocatalysts.