We develop a 3D nanowires-array-support/active cobalt plating to grow cobalt-phytate nanoplates (3D-NA/Co/CoNPAs) as an advanced oxygen-evolving electrode. The constructed structure exhibits greatly enhanced catalytic activity (j=10 mA cm-2 = 265 mV) and good stability (current retention >94% after electrolysis of 6 h). Moreover, the Co-phytate grown on 3D-NA/Co is also used as the anode in a two-electrode configured alkaline electrolyzer with the sharp decline of energy consumption (41.55 KWh kg-1Hydrogen) for hydrogen production. We then determine the insight of the electrocatalytic process toward water oxidation on our prepared electrode. First, the results reveal that the 3D-substrate can obviously reduce the resistance for the electron transfer during the oxygen evolution turnover. In addition, the introduction of active cobalt plating will lead to the self-supported Co-phytate nanostructures generation, which can significantly enlarge the electrochemically active surface area (EASA). Further, the electrode after catalysis is also characterized, and we find that the nanostructured cobalt oxo/hydroxide are densely grown on the original Co-phytate nanoplates. These core/shell nanocomposites not only own higher EASA but also obviously decrease the free-energy change during the O-O formation of the CoO6-based intermediate affected by the phytate group.