All-inorganic cesium lead halide perovskite nanostructure CsPbBr3 quantum dots have brought extensive attention in photoelectric applications. In this paper, CsPbBr3 quantum dots were synthesized with the diameter ranges from 8.7 to 11.8 nm by adjusting reaction temperature from 140 to 180 degrees C. In addition, for the mono-disperse CsPbBr3 nanocrystals, it was found that radiative lifetime exists between 5 and 20 ns and PL decay lifetimes ranges from 4 to 11 ns, and their PL mechanism was studied thoroughly.