Efficient and stable electrocatalytic hydrogen evolution reaction (HER) at high current densities is highly desirable for industrial-scale hydrogen production, which is yet challenging, because of the electrocatalyst with short lifespans during the acidic HER process. Here, a controllable preparation technique is successfully developed to synthesize PdPtRuRhAu high-entropy alloys (HEAs) of various sizes, within the 3.14 nm particles (HEA-3.14) demonstrating exceptional catalytic performance and stable hydrogen production at current densities of -500 and -1000 mA·cm