Spinel LiMn2O4 was synthesized via a solid state reaction, and modified with Al2O3 thin layers by a chemical deposition method. The electrochemical performances of the as-prepared samples were investigated with cyclic voltammetry (CV) and charge-discharge test. It is found that the Al2O3-coated LiMn2O4 help dramatically retaining the discharge capacity upon long-term cycling. The influences of the heat-treating temperature and the coating amount are discussed and compared. The optimized sample is 1% Al2O3/ LiMn2O4 heat-treated at 500oC, which has an initial discharge capacity of 116mAh/g, and a very slight capacity loss of 1.7% at the 50th cycle.