Mn2+ ion doped all-inorganic perovskite (Mn2+∶CsPbX3, X=Cl,Br) nanocrystals have been promising for a wide range of applications in solid-state lighting, photoelectric detection and imaging due to their advantages of wide emission bands, long Stokes shifts and high quantum yields. However, the quantum yield of Mn2+-doped perovskite crystals hardly exceeds 70%. How to improve the luminous efficiency while regulating the Mn ion emission centers becomes the key to build high-quality white LEDs. In this paper, highly efficient luminescent Cd2+ and Mn2+ co-doped CsPbCl3 nanocrystals were obtained by CdCl2 post-treatment technique with cation exchange at room temperature. The emission wavelength of Mn can be continuously tuned from 604nm to 624nm to achieve stable red light emission. Cd ion doping improves the crystal field environment of Mn-Cl octahedra and increases the Mn decay lifetime to 1.32ms. In addition, warm white light-emitting diodes (WLEDs) with high color rendering index were constructed by green CsPbBr3 nanocrystals and blue-orange bicolor Mn∶CsPb(ClBr)3 nanocrystals. The lumen efficiency reaches 60lm/W and the color rendering index exceeds 85.