Rareearth elements (REEs), with their unique 4f electronic configurations,tunable valence states,and exceptional oxygen affinity,demonstrate irreplaceable regulatory value in the rational design of electrocatalysts for water electrolysis.This review systematically elucidates the key strategies,mechanistic insights, and recent advances in REE⁃enhanced electrocatalytic performance.First,the modulation effect of REEs on the electronic structure of catalysts and the mechanism of performance enhancement are analyzed in depth.Second,the research progress of three modulation strategies⁃rare⁃earth atomic doping, heterointerfacial construction and dynamic surface reconstruction⁃for improving the performance of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is discussed in detail.Particular attention is paid to revealing the intrinsic correlation between REE⁃induced electronic structure modulation and improved catalytic performance.Finally,critical challenges confronting current research are identified,and future research directions are proposed,including the rational design of rare⁃earth⁃based electrocatalysts,in⁃situ characterization techniques,exploration of multi⁃factor synergistic mechanisms,and recycling of rare earth resources.This work provides systematic research insights to advance the industrialization of water electrolysis for hydrogen production.