Based on the element immiscibility of Ni-Ru, xRu@Ni3B (x = 0, 0.2, 0.5, 1.0) were facilely synthesized through a one-step dealloying method. Of them, 1.0Ru@Ni3B requires overpotentials of 40 ± 0.2 and 72 ± 0.3 mV to reach a current density of -20 mA cm-2 for acidic and alkaline hydrogen evolution reaction, respectively, which are close to or even better than those of metallic Pt foil. In addition, it could maintain superior catalytic and chemical stability after 24 hours of testing. This work provides a promising strategy for improving the atomic utilization efficiency of highly active noble metals toward the hydrogen evolution reaction (HER).