High　entropy　materials　(HEMs)　have　developed　rapidly　in　the　field　of　electrocatalytic　water-electrolysis　for　oxygen　evolution　reaction　(OER)　and　hydrogen　evolution　reaction　(HER)　due　to　their　unique　properties.　In　particular,　HEM　catalysts　are　composed　of　many　elements.　Therefore,　they　have　rich　active　sites　and　enhanced　entropy　stability　relative　to　single　atoms.　In　this　paper,　the　preparation　strategies　and　applications　of　HEM　catalysts　in　electrochemical　water-electrolysis　are　reviewed　to　explore　the　stabilization　of　HEMs　and　their　catalytic　mechanisms　as　well　as　their　application　in　support　green　hydrogen　production.　First,　the　concept　and　four　characteristics　of　HEMs　are　introduced　based　on　entropy　and　composition.　Then,　synthetic　strategies　of　HEM　catalysts　are　systematically　reviewed　in　terms　of　the　categories　of　bottom-up　and　top-down.　The　application　of　HEMs　as　catalysts　for　electrochemical　water-electrolysis　in　recent　years　is　emphatically　discussed,　and　the　mechanisms　of　improving　the　performance　of　electrocatalysis　is　expounded　by　combining　theoretical　calculation　technology　and　ex-situ/in　situ　characterization　experiments.　Finally,　the　application　prospect　of　HEMs　is　proposed　to　conquer　the　challenges　in　HEM　catalyst　fabrications　and　applications.　©　Higher　Education　Press　2023.