Metal-organic frameworks (MOFs), as promising precursors for specific morphologies nanomaterials for oxygen evolution reaction (OER), become a new research focus. Ultrathin NiCoFe-MOF nanosheets are synthesized on the Ni foam substrate by solvothermal method and becomes converted into metal hydrogen (hydroxy) oxide on the basis of retaining the morphology of the nanosheets under the In-situ electrochemical conditions. The overpotential of 189 mV at a current density of 10 mA?cm-2 and a Tafel slope of 35 mV/dec in 1 M KOH electrolyte, long-term electrolysis experiment also signifies its excellent stability. In-situ Raman spectroscopic reveals that the high activity of the OER derives from the "active oxygen" species intermediates.