Abstract: Blue luminescent CsPbBr₃ quantum dots have attracted much attention due to their high quantum yield. CsPbBr₃ quantum dots with highly efficient blue-emitting were synthesized by two-step supersaturated recrystallization at room temperature. The proposed method could control the particle size within 5 nm， resulting in strong quantum confinement effect of the product. The morphology， structure and basic optical properties of the samples were studied by transmission electron microscope， X-ray diffractometer， ultraviolet visible fluorescence graduator and fluorescence spectrometer. The results showed that the size of quantum dots can be adjusted by adding different proportions of chlorobenzene solvent， and then the band gap can be adjusted. The prepared CsPbBr₃ quantum dots had excellent optical properties， and the blue light-emitting diodes made from CsPbBr₃ quantum dots exhibited high photoluminescence intensity， which has a good application prospect in optoelectronic devices.