Perovskite　quantum　dots　light-emitting　diodes　(PQLEDs),　due　to　the　advantages　of　high　luminous　efficiency,　high　color　purity,　adjustable　spectral　range,　etc.,　has　an　excellent　prospect　in　the　next　generation　of　high-definition　displays.　As　an　indispensable　part　of　displays,　blue　PQLEDs　are　usually　achieved　by　mixing　halogen,　which,　however,　will　lead　to　halogen　ion　migration　and　phase　separation　of　perovskite　material　at　high　temperature　and　bias　pressure,　thus　make　the　electroluminescent　spectrum　redshift.　In　this　manuscript,　we　propose　a　strategy　to　inhibit　phase　separation　of　blue　perovskite　quantum　dots　(PQDs)　by　introducing　alkali　metal,　and　obtain　stable　perovskite　quantum　dot　light-emitting　diodes.　The　PQLEDs　based　on　this　strategy　show　an　external　quantum　efficiency　(EQE)　of　1.87%　and　a　brightness　of　3757　cd　m−2,　and　can　still　guarantee　stable　electroluminescence　(EL)　spectra　at　a　bias　of　up　to　14　V.　The　work　is　beneficial　for　probing　into　the　mechanism　of　suppressing　the　phase　separation　of　mixed　halogen　blue　PQDs　and　offer　a　promising　strategy　to　enhance　the　color　stability　of　blue　PQLEDs.　©　2022　Elsevier　B.V.