Abstract: The preparation of electrocatalyst for high efficiency hydrogen evolution reaction (HER) is of great significance to the large-scale promotion of hydrogen energy. In this paper, using sodium carboxymethyl cellulose (CMC-NA) and RuCl₃ as raw materials, Ru-CMC-Na hydrogel was prepared by the coordination of Ru ions with CMC-Na in solution. Then, porous carbon supported Ru single atom and Ru nanocluster catalyst Ru_SA+NC/C-2 was prepared by freeze-drying, high temperature annealing and pickling. The catalyst Ru_SA+NC/C-2 shows excellent HER activity and stability in both acidic and alkaline electrolytes, reaching 10 mA·cm⁻² current density at 20 mV and 23 mV, respectively. After 12 h chronoamperometry test, the activity of Ru_SA+NC/C-2 shows no obvious attenuation. The mass activity of Ru_SA+NC/C-2 is 5.8 times that of commercial Pt/C when the overpotential is 0.05 V in 1 mol/L KOH electrolyte. The physical characterization of Ru_SA+NC/C-2 catalyst shows that the porous structure and large specific surface area of Ru_SA+NC/C-2 catalyst can expose more active sites. Ru single atom and Ru nanocluster structure improve the utilization rate of Ru atom. XPS analysis shows that there is a strong interaction between Ru and carbon support, resulting in the formation of electron-deficient Ru, thus improving HER activity of the catalyst.