Ruthenium metal has been widely utilized as an efficient catalyst for hydrogen production electrocatalytic water splitting. However, its high cost and low atomic utilization efficiency are regarded as significant limitations for practical applications. In this study, Ru nanoparticles with sizes ranging from 2 to 10 nm were grown in situ onto the modified surface of sepiolite, a cheap mineral with limited electrical conductivity, via a low-cost synthetic strategy under mild conditions. The novelly synthesized catalyst shows a specific surface area of 422.1 m2/g with a pore volume of 0.213 cm3/g, and the multi-level pore structure of carbonized modified sepiolite is maintained. XPS and FTIR results indicate that abundant C-O-Ru functional groups. The synthesized composite exhibits excellent HER performance in acidic electrolytes, with an overpotential of 38 mV (a 10 mA/cm2 current density), even lower than commercial platinum-carbon catalysts (39 mV). And stability of the catalyst is maintained after an 18-hour cycle, with a high-frequency region of the Nyquist diagram and minimal impedance arc diameter. Theoretical calculations also demonstrate that the synthesized catalyst exhibits considerable water adsorption capability (-0.925eV) while maintaining a near-optimal ΔGH* value (-0.14eV), which is favor of Volmer step and efficient hydrogen desorption.