Cesium　lead　halide　(CsPbX3,　X　=　Cl,　Br,　I)　perovskite　quantum　dots　(PQDs)　have　attracted　extensive　attention　due　to　their　high　crystal　structure　stability.　However,　a　large　number　of　defects　generally　exist　on　the　surface　of　PQDs,　which　results　in　non-radiative　recombination　and　affects　the　electrical　performance　of　their　devices.　Here,　we　report　a　simple　and　feasible　hybrid　ligand　passivation　strategy　to　modify　PQDs　surface　defects.　Guanidine　bromide　(GABr)　and　didecyldimethyl　ammonium　bromide　(DDAB10)　were　dissolved　in　toluene　to　modify　the　surface　trap　state　of　PQDs.　The　post-treatment　strategy　effectively　inhibits　vacancy　defects　and　improves　elec-trical　performance.　The　strong　affinity　(N-H...Br)　between　guanidine　ion　and　halogen　not　only　reduces　the　defect　density　of　PQDs,　but　also　improves　their　carrier　mobility.　The　results　also　show　that　the　guanidine　ion　is　closely　bonded　to　the　surface　of　PQDs,　the　fluorescence　lifetime　is　longer,　and　the　defect　density　is　smaller.　Finally,　a　green　perovskite　light-emitting　diode　(PeLED)　device　with　an　EQE　of　10.02%　and　current　efficiency　of　36.4　cd/A　was　obtained.