Oxygen evolution reaction is a significant half-reaction for water splitting, while its sluggish kinetics and high-cost catalyst hinder the commercial application. In this work, we report a novel nanocoral-like NiSe2/g-C3N4 composite as highly efficient catalyst for water oxidation in 1.0 M KOH solution. Based on the support of multi-layered g-C3N4, NiSe2/g-C3N4 composite exhibits favorable electrocatalytic performances with low overpotential of 290 mV at current density of 40 mA cm(-2) and low onset potential of 1.38 V (vs. RHE). In addition, NiSe2/g-C3N4 composite delivers higher current density (199 mA cm(-2)) than those of pure NiSe2 (142 mA cm(-2)) and multi-layered g-C3N4 (112 mA cm(-2)) at potential of 2.0 V (vs. RHE). Furthermore, NiSe2/g-C3N4 composite exhibits an excellent long-term electrochemical stability for 10 h. The outstanding electrocatalytic properties above suggest that NiSe2/g-C3N4 composite is a candidate for the substitution of noble metal based catalyst for oxygen evolution reaction.