Abstract: The spinel LiMn2O4 for lithium-ion battery was prepared by sol-gel method using Mn(Ac)2·4H2O, (AC)Li·2H2O and harmless low-molecule citric acid as raw materials. The mechanism of synthesizing LiMn2O4 with dry gel was found by TGA-DTA analysis at different heating rates. In the process of dry gel burning, large quantity of the LiMn2O4 were formed because of the small grain size of the products Mn3O4 and Li2O2 resulting from burning, and the residual Mn3O4 and Li2O2 reacted completely at about 300°C, thus lowering greatly the synthesizing temperature. XRD pattern of the LiMn2O4 showed that the product samples are all of a pure phase with spinel-type structure, sharp peak and perfect crystalline. Investigating the effect of pH values on the grain size and electrochemical property of samples, the SEM analysis showed that the electrochemical capacity of the LiMn2O4 samples increases with the increasing pH value, of which the grain size distribution is uniform at a sub-micron level if pH value is 6.0. The charge/discharge testing result at 10% current of initial discharge capacity and 3.30-4.35 V showed that the initial discharge capacity of the synthesized samples is 121.0 mAh/g. It implies a good electrochemical property.