The invention discloses a method of preparing an anion co-doped lithium-rich manganese-based solid solution anode material, which belongs to the field of lithium ion battery anode materials. Soluble metal salt and soluble phosphate are dissolved in secondary deionized water to prepare a mixture solution; a polymer is dissolved in ethanol to prepare a polymer solution; the polymer solution and themixture solution are then mixed uniformly, and a precursor is prepared by using an electrospinning device; and finally, the obtained precursor and fluoride are uniformly mixed in a molar ratio and calcined in an oxygen atmosphere to obtain the anion co-doped lithium-rich manganese-based solid solution anode material. The preparation method is simple, the reaction process is quick and simple, doping the phosphate of the anode material is added by the precursor, the doping is more uniform, step doping of fluoride is carried out during the calcining process through high temperature induction, surface side reaction and oxygen loss during the charging and discharging process of the first cycle are suppressed, the first cycle efficiency is improved, the anode material structure is effectively stabilized by polyanion, and the cycle stability of the material is improved.