The invention discloses a preparation method of a 
fluorine-doped 
lithium-rich 
manganese-based positive 
electrode material. The 
lithium-rich 
manganese-based positive 
electrode material has a chemical general formula of xLi2MnO3.(1-x) LiMO<2-y>F<2y>, wherein x is larger than or equal to 0.1 and smaller than or equal to 0.9, y is larger than 0 and smaller than or equal to 0.05, and M is one or more of Ni, Co, Mn, Cr, Fe, Ti, Mo, Ru, V, Nb, Zr and Sn. The preparation method comprises the following steps of: preparing a 
fluorine-doped 
lithium-rich 
manganese-based precursor through a 
precipitation reaction by adopting soluble 
metal salt, a precipitator, a soluble 
fluorine-containing compound and water; and uniformly mixing the fluorine-doped lithium-rich manganese-based precursor with a lithium salt, and carrying out presintering and high-temperature 
sintering to obtain the fluorine-doped lithium-rich manganese-based positive 
electrode material. According to the method, the soluble fluorine-containing compound is used as a fluorine source, 
fluorine doping is synchronously realized during 
coprecipitation of the lithium-rich manganese-based precursor, the 
doping uniformity is relatively good, and the cycle performance of the doped lithium-rich material is greatly improved.