Aiming at the problems of low capacity retention rate and poor rate performance of Li-rich manganese-based materials, Al2O3 was used as the Al source, and A13+ doped Li1.104-3xAlxMn0.56Ni0.24O2 (0≤x≤0.01) positive electrode material was prepared by high temperature solid phase method. XRD showed that doped Al3+ successfully replaced part of Li+ into the lattice of Li-rich manganese-based cathode materials. Electrochemical performance tests showed that Al3+ doping inhibited the voltage decay of Li1.104Mn0.56Ni0.24O2 material during cycling, while improving its cycle performance and rate performance. After 100 cycles of Li1.0965Al0.0025Mn0.56Ni0.24O2 material at 0.2 C current density, the discharge specific capacity was 234.42 mA·h/g, and its capacity retention rate was as high as 86.32 %, while the material capacity retention rate of undoped Li1.104Mn0.56Ni0.24O2 was only 67.27 %.