The reaction process during synthesis of LiMn2 O4 with LiOH. H2 O and MnO2 was studied by means of DTA in dynamical air atmosphere, and it could be applied as an important theoretical principle for preparing LiMn2 O4. The active energies of four reaction processes were obtained with Doyle-Ozawa method and Kissinger method as follows: 66.299, 72.640, 128.111 and 113.876 kJ. mol-1, respectively. Reaction orders,frequency factors and kinetic equations of each reaction were determined by using Kissinger method. XRD, SEM and TEM showed that the synthesized LiMn2 O4 is a pure phase, with regular appearance and higher ratio-surface.``