The invention provides an improved method for preparing layered enriched lithium-manganese-nickel oxide by low-heat solid-phase reaction. The method comprises the following steps: weighing lithium hydroxide monohydrate, nickel acetate and manganese acetate, and oxalic acid dihydrate according to the stoichiometry as follows: Li1+xMnyNi1-x-yO2, x being more than 0 and less than or equal to 1 / 3, y being more than 0 and less than 1, and x+y being more than 0 and less than 1 (wherein the mole ratio of LiOH.H2O to C2H2O4.2H2O is 1:1-1.2), and adding into a ball milling tank together for balling milling for 0.5-2h; obtaining slurry, adding deionized water in the slurry to adjust concentration, spraying and drying the slurry, and roasting the dried powder to obtain the final product -Li1+xMnyNil-x-yO2. The improved method has the following advantages: the process flow is short, the component of the material can be accurately controlled, the problems of material loss and inaccurate stoichiometry caused by repeatedly washing the product in a liquid phase method are overcome, the generation of a large quantity of waste water is avoided; simultaneously, the shape and particle size of a synthesized material can be controlled, the engineering index requirement can be achieved, the impurity pollution caused by dependence of a synthetic material by a solid phase method on crushing process can be overcome, the enriched lithium-manganese-nickel oxide has typical layered structure property, the particle size is 3-12mum, the specific capacity is high, and the cyclic performance is stable.