The discomposing kinetics of lithium manganese oxides precursor in dynamical air atmosphere was studied by means of DTA with different heating rates, and it could be applied as an important theoretical principle for preparing LiMn2O4. The active energies of four reaction processes were obtained with Doyle–Ozawa method and Kissinger method as follows: 69.831, 165.093, 326.128, and 645.983kJmol−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 LiMn2O4 using the precursor is a pure phase, with regular appearance and higher ratio-surface.