Abstract: Provided are a high-quality, lithium-rich and manganese-based positive electrode material for a lithium ion battery and a method for synthesizing same. The method comprises the following steps: preparing a precursor by complexing an amino acid and a nickel-cobalt-manganese metal, mixing the above-mentioned precursor with a lithium salt, and subjecting same to ball-milling, drying and calcination to obtain a finished product. The amino acid is used as a complexing agent, benefiting the coprecipitation of the three transition metals, achieving the uniform distribution of each metal element in a material, improving the comprehensive electrochemical performance of a lithium-rich and manganese-based material, and improving the quality of the material. The lithium-rich and manganese-based material prepared by the method has characteristics such as a high tapped density, a high compaction density, and a better electrochemical performance.