Ni3N@C nanocomposite was prepared by a simple one-step low-temperature pyrolysis method with nickel acetate in flowing ammonia. The spherical Ni3N nanoparticles were uniformly coated with a carbon protective layer formed in-situ with a thickness of 10 nm, which shows excellent catalytic activity for overall water splitting in alkaline solution. The experimental results showed that the initial potential for hydrogen evolution reaction (HER) was -0.06 V (versus reversible hydrogen electrode, vs RHE), and the overpotential (η) was 284mV at the current density of 10mA cm-2; the initial potential for oxygen evolution reaction (OER) was 1.53 V vs RHE, and η was 390 mV at the current density of 10 mA cm-2. In addition, Ni3N@C had excellent stability for overall water splitting in alkaline solution. The excellent activity and high stability of the catalyst are due to the high intrinsic activity of Ni3N as well as the formation of carbon coating layer, which not only improves the conductivity of the material and accelerates the transfer of electrons and protons, but also protects Ni3N from corrosion in alkaline electrolyte. In a word, we provide a simple, economical and low-temperature sustaining method to prepare Ni3N to be used in water splitting, and the preparation method can also be used to prepare other promising bifunctional electrocatalysts for energy conversion field.