Doping metal ions into lead halide perovskite nanocrystals is one of the most efficient strategies to control their photoelectric properties. Here, we develop a simple and low-cost route to synthesize the high-quality alkaline-earth metal ion (AE2+)-doped CsPbBr3 nanocrystals at room temperature. The almost 100% promoted photoluminescence quantum yield behavior of AE2+-doped CsPbBr3 nanocrystals is demonstrated by an ultrafast dynamics study and theoretical calculations on the dopant defect formation energies and electronic properties. The AE2+ dopants can promote the radiation recombination of carriers by essentially reducing the carriers trapped into intraband and interband defect states and promote the intraband coupling. Furthermore, Br– and Pb2+ vacancies can be eliminated to enhance the short-range order of the CsPbBr3 lattice and enrich the conduction band edge states, leading to the photoluminescence enhancement of CsPbBr3 nanocrystals. Our studies provide new insights into the mechanism of AE2+-doped effects and present guiding strategies for improving the optical performance of doped perovskite nanocrystals.