Abstract: Spinel LiMn2O4 cathode material doped with Cr3+ and F－ was prepared by solid-state reaction，and the material was modified by coating Al2O3 on its surface. The morphology and structure were characterized with scanning electron micrograph and X-ray diffraction，and the electrochemical properties were studied with charging-discharging test and A.C impedance test. The results showed that both materials doped with Cr3+ and F- and coated with Al2O3 had a spinel structure. With increasing level of doping and coating，their initial discharging capacity reduced，but their cycling performance was greatly improved. The 1st discharging capacities of LiMn2O4，LiMn1.9Cr0.1O3.9F0.1 and LiMn1.9Cr0.1O3.9F0.1/coated 0.3%Al2O3 were 125.3，117.5 and 113.7mA·h·g－1 respectively，after 25 cycles，their capacity retentions were 82.7%，91.5% and 93.6% respectively. When cycling at 55℃，the electrochemical properties of the material coated with Al2O3 was the best，its discharging capacity and capacity retention after 25 cycles were 104.2 mA·h·g－1 and 92.1% respectively.