The design of low-cost and robust electrocatalysts with rich active sites remains challenging for improving the efficiency of water oxidation. Herein, ternary Ni-Co-Mo oxide films were uniformly synthesized on Cu foil via simple electrochemical deposition method. After surface reconstruction, the robust amorphous-crystalline (a-c) Ni(Co) heterostructures with rich oxygen vacancies were achieved. Accordingly, the as-obtained surface-reconstructed heterostructure catalysts exhibited a superior OER activity with overpotential at 20 mA/cm2 as low as 308 mV and a small Tafel slope of 90 mV/dec. Moreover, a negligible activity degradation was observed for the heterostructure catalyst continuously catalyzing OER process over 24 h, highlighting the structural robustness of the self-reconstructed Ni-Co-Mo catalyst for practically electrocatalytic applications.