Ni-Mg co-doped LiNi0.03Mg0.10Mn1.87O4 cathode material was synthesized by solid-state combustion method at 500℃ for 1 h and further calcined at 650℃ for 6 h. The structure, morphology, phase and electrochemical properties of the material were tested by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction spectrometry (XPS) and electrochemical tests. The results show that the LiNi0.03Mg0.10Mn1.87O4 has a cubic spinel structure with a particle size of 100-200 nm, which is a polyhedral morphology. The synthesized LiNi_0.03Mg0.10Mn1.87O4 has good electrochemical performance with initial discharge capacity of 107.6 mAh.g-1 at 1 C, and the first discharge capacity of 10 C is 68.7 mAh.g-1. The initial discharge capacity is 103.7 mAh?g-1 at a high temperature of 55℃. CV and EIS tests show that the LiNi0.03Mg0.10Mn1.87O4 has a large lithium ion diffusion coefficient of 1.038×10-11 cm2.s-1 and a small activation energy of 32.69 kJ.mol-1. The material after 1000 cycles shows that the crystal structure and particle morphology are basically unchanged, doping appropriate amounts of Ni and Mg ions can effectively improve the capacity attenuation and structural stability of the spinel LiMn2O4, thereby suppressing the Jahn-Teller effect.