Manganese minerals were synthesized by the reaction between KMnO₄ and bivalent manganese salts. Crystal structure characteristics of the synthetic minerals were investigated by means of X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). The effects of mole ratio R of Mn²⁺ to Mn⁷⁺(1:1, 1:2, 1:3 and 1:4 respectively), synthetic temperature (30℃, 50℃, 70℃, 90℃ and 110℃ respectively), and anionic species (Cl^-, SO₄^2-, and NO₃^- respectively) on the formation of the minerals were discussed. The results showd that the synthetic minerals were transformed from cryptomelane to birnessite with the decrease of R from 1:1 to 1:4, and the average oxidation state of manganese (AOS_Mn) increased correspondingly. Anionic species of the reactants affected the type and crystalline of the synthetic minerals. Within the experimental synthetic temperature (30～110℃), the crystallinity and AOS_Mn of the synthetic minerals rose slightly as the temperature increased.