The preparation of CsPbX3 nanoplatelets and the investigation of their optical properties have been rarely reported. Herein, the successful development of all-inorganic CsPbX3 (X = Cl, Br, or I) perovskite quantum dots has been achieved and their unique optical and electrical properties are discussed. apre-dissolution assisted solvothermal reaction was developed to synthesize ultrathin (∼3 nm) CsPbBr3 nanoplatelets with strong exciton absorption, with a 0.41 eV blue-shifted emission relative to that of CsPbBr3 nanocrystals and a high quantum yield of 28%. Anion exchange allowed the variation of the halogen content of the nanoplatelets and allowed them to retain their shape and size and achieve multi-color emission.