The　development　of　pure-blue　perovskite　light-emitting　diodes　(PeLEDs)　faces　challenges　of　spectral　stability　and　low　external　quantum　efficiency　(EQE)　due　to　phase　separation　in　mixed　halide　compositions.　Perovskite　quantum　dots　(QDs)　with　strong　confinement　effects　are　promising　alternatives　to　achieve　high-quality　pure-blue　PeLEDs,　yet　their　performance　is　often　hindered　by　the　poor　size　distribution　and　high　trap　density.　A　strategy　combining　thermodynamic　control　with　a　polishing-driven　ligand　exchange　process　to　produce　high-quality　QDs　is　developed.　The　strongly-confined　pure-blue　(approximate　to　470　nm)　CsPbBr3　QDs　exhibit　narrow　size　distribution　(12%　dispersion)　and　are　achieved　in　Br-rich　ion　environment　based　on　growth　thermodynamic　control.　Subsequent　polishing-driven　ligand　exchange　process　removes　imperfect　surface　sites　and　replaces　initial　long-chain　organic　ligands　with　short-chain　benzene　ligands.　The　resulting　QDs　exhibit　high　photoluminescence　quantum　yield　(PLQY)　to　near-unity.　The　resulting　PeLEDs　exhibit　a　pure-blue　electroluminescence　(EL)　emission　at　472　nm　with　narrow　full-width　at　half-maximum　(FWHM)　of　25　nm,　achieving　a　maximum　EQE　of　10.7%　and　a　bright　maximum　luminance　of　7697　cd　m(-2).　The　pure-blue　PeLEDs　show　ultrahigh　spectral　stability　under　high　voltage,　a　low　roll-off　of　EQE,　and　an　operational　half-lifetime　(T-50)　of　127　min　at　an　initial　luminance　of　103　cd　m(-2)　under　continuous　operation.