Exploring a simple, fast, solvent-free synthetic method for large-scale preparation of cheap, highly active electrocatalysts for industrial hydrogen evolution reaction is one of the most promising work today. In this work, a simple, fast and solvent-free microwave pyrolysis method is used to synthesize ultra-small (3.5 nm) Ru-Mo2C@CNT catalyst with heterogeneous structure and strong metal-support interaction in one step. The Ru-Mo2C@CNT catalyst only exhibits an overpotential of 15 mV at a current density of 10 mA cm-2, and exhibits a large turnover frequency value up to 21.9 s-1 under an overpotential of 100 mV in 1.0 M KOH. In addition, this catalyst can reach high current densities of 500 mA cm-2 and 1000 mA cm-2 at low overpotentials of 56 mV and 78 mV respectively, and it displays high stability of 1000 h. This work provides a feasible way for the reasonable design of other large-scale production catalysts.