Manganese　Hexacyanoferrate　(Mn　&　horbar;HCF)　is　a　preferred　cathode　material　for　sodium-ion　batteries　used　in　large-scale　energy　storage.　However,　the　inherent　vacancies　and　the　presence　of　H2O　within　the　imperfect　crystal　structure　of　Mn　&　horbar;HCF　lead　to　material　failure　and　interface　failure　when　used　as　a　cathode.　Addressing　the　challenge　of　constructing　a　stable　cathode　is　an　urgent　scientific　problem　that　needs　to　be　solved　to　enhance　the　performance　and　lifespan　of　these　batteries.　In　this　review,　the　crystal　structure　of　Mn　&　horbar;HCF　is　first　introduced,　explaining　the　formation　mechanism　of　vacancies　and　exploring　the　various　ways　in　which　H2O　molecules　can　be　present　within　the　crystal　structure.　Then　comprehensively　summarize　the　mechanisms　of　material　and　interfacial　failure　in　Mn　&　horbar;HCF,　highlighting　the　key　factors　contributing　to　these　issues.　Additionally,　eight　modification　strategies　designed　to　address　these　failure　mechanisms　are　encapsulated,　including　vacancy　regulation,　transition　metal　substitution,　high　entropy,　the　pillar　effect,　interstitial　H2O　removal,　surface　coating,　surface　vacancy　repair,　and　cathode　electrolyte　interphase　reinforcement.　This　comprehensive　review　of　the　current　research　advances　on　Mn　&　horbar;HCF　aims　to　provide　valuable　guidance　and　direction　for　addressing　the　existing　challenges　in　their　application　within　SIBs.