As a new type of colloidal nanocrystals, perovskite quantum dots (QDs) have received widespread attention. Water and oxygen in the air can affect the luminous efficiency of quantum dots, which can degrade the surface of QDs and affect their luminescence efficiency. Herein we discuss the synthesis of high-quality QDs using an uncomplicated coating method by which an ultrathin epitaxial Al self-passivation layer bearing homogeneous ligands can be coated on the QDs. The core/shell perovskite QDs maintain high luminescence efficiency and photostability. The CsPbBr3/2ZnS/Al QDs were only attenuated by 10% after 14 h of exposure to LED light. The temperature-dependent photoluminescence properties of the all-inorganic perovskite QDs, such as the PL intensity, emission peak position, and the full width at half maximum (FWHM), were investigated. The results indicated that the activation energy of QDs increases with the increase of the number of ZnS shell layers, its stability increases significantly. The introduction of Al does not change the luminescence mechanism of QDs. Finally, we have made flexible light-emitting device with CsPbBr3/2ZnS/Al QDs.