The development of high catalytic activity and cheap catalyst is the key of catalytic decomposition of water to produce hydrogen. The transition metal nickel nitride (Ni3N) has excellent thermal/chemical stability, electrochemical activity and noble metal-like properties, which attracts more and more researchers’ interest. However, in the process of Ni3N alkaline electrocatalysis of hydrogen evolution reaction, the dissociation efficiency of water is low, and the adsorption of the intermediate proton is too strong, which result in the much lower performance of Ni3N than Pt catalyst. In this work, Ru-doped porous Ni3N nanosheets (Ni3N/Ru) were prepared successfully by two-step method of hydrothermal and nitriding process. The composition, morphology and structure of Ni3N/Ru materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The catalytic mechanism was analyzed by X-ray photoelectron diffractometer (XPS), and the effect of Ru doping amount on the morphology and electrocatalytic performance of Ni3N materials was also studied. The results show that Ni3N loaded with 6.30%Ru needs only an overpotential of 49 mV to drive the current density of 10 mA·m-2 in 1 mol/L KOH electrolyte, which is comparable to commercial Pt/C (46 mV@10 mA·cm-2). The Ni3N/Ru were then assembled into a two-electrode system for overall water splitting, and the cell voltage required to reach the current density of 10 mA·cm-2 is only 1.54 V. The outstanding catalytic performance is attributed to the fact that Ru doping Ni3N effectively improves the dissociation of water, reduces the electron cloud density of Ni and N in Ni3N, promotes the formation process of adsorbed hydrogen intermediates (H++e-=H*), improves hydrogen evolution reaction kinetics, and thus enhances its electrocatalytic performance.