Perovskite　nanocrystals　have　absorbed　increasing　interest,　especially　in　the　field　of　optoelectronics,　owing　to　their　unique　characteristics,　including　their　tunable　luminescence　range,　robust　solution　processability,　facile　synthesis,　and　so　on.　However,　in　practice,　due　to　the　inherent　instability　of　the　traditional　long-chain　insulating　ligands　surrounding　perovskite　quantum　dots　(PeQDs),　the　performance　of　the　as-fabricated　QLED　is　relatively　disappointing.　Herein,　the　zwitterion　3-(decyldimethylammonio)propanesulfonate　(DLPS)　with　the　capability　of　double　passivating　perovskite　quantum　dots　could　effectively　replace　the　original　long-chain　ligand　simply　through　a　multistep　post-treatment　strategy　to　finally　inhibit　the　formation　of　defects.　It　was　indicated　from　theexperimental　results　that　the　DLPS,　as　one　type　of　ligand　with　the　bimolecular　ion,　was　very　adavntageous　in　replacing　long-chain　ligands　and　further　suppressing　the　formation　of　defects.　Finally,　the　perovskite　quantum　dots　with　greatly　enhanced　PLQY　as　high　as　98%　were　effectively　achieved.　Additionally,　the　colloidal　stability　of　the　corresponding　PeQDs　has　been　significantly　enhanced,　and　a　transparent　colloidal　solution　was　obtained　after　45　days　under　ambient　conditions.　Finally,　the　as-fabricated　QLEDs　based　on　the　ligand-exchanged　PeQDs　exhibited　a　maximum　brightness　of　9464　cd/m(2)　and　an　EQE　of　12.17%.