Purification process of quantum dots could exert great effect on the optical and electrical properties of Cesium lead bromine （CsPbBr₃） perovskite quantum dots （PQDs）. In this paper， a simple and feasible complex ligand passivation strategy was proposed to modify the surface defects of PQDs. Guanidine bromide （GuaBr） and didecyl dimethyl ammonium bromide （DDeAB） were introduced to modify perovskite quantum dots in the purification process. This ligand passivation strategy could effectively suppress vacancy defects and improve its electrical performance. Finally， based on the quantum dots modified by complex ligands， the green PeLED device could show low performance roll and the maximum brightness of 15 786 cd/m².