Potassium　manganese-based　Prussian　blue　analogs　(KMn-HCF)　hold　great　potential　as　cathodes　for　sodium-ion　batteries　(SIBs).　However,　the　rapid　synthesis　process　often　results　in　excessively　small　particle　sizes,　increasing　surface　area　and　thereby　intensifying　side　reactions　with　the　electrolyte,　which　can　damage　the　cathode　electrolyte　interface　(CEI)　and　diminish　cycling　stability.　Herein,　we　designed　a　topological　phase　transition　strategy　to　assemble　small　KMn-HCF　particles　into　a　600　nm　cubic　superstructure.　Structurally,　the　assembled　structure　in　KMn-HCF　significantly　improves　the　cycling　stability　and　durability　of　KMn-HCF　as　a　SIB　cathode　by　reducing　defects,　enhancing　the　uniformity　and　stability　of　the　CEI　layer,　minimizing　contact　with　the　electrolyte,　and　reinforcing　structural　integrity.　From　a　compositional　perspective,　KMn-HCF　exhibits　lower　Jahn-Teller　distortion,　reducing　overall　lattice　distortion　while　allowing　larger　K+　to　act　as　pillars,　supporting　the　Mn-HCF　framework　and　preventing　capacity　degradation　caused　by　structural　deterioration.　The　robust　CEI　layer　formed　in　the　KMn-HCF　cubic　superstructure　delivered　stable　charge-discharge　voltage　profiles　and　reversible　plateaus,　achieving　a　capacity　retention　of　88.4%/89.1%　after　1000　cycles　at　current　densities　of　0.1　and　0.5　A　g-1,　respectively.