One of the characteristics of solid organic compounds and especially organic explosives is thermal behavior and kinetic of thermal decomposition. The activation energy, Arrhenius constant and model of solid state reaction as kinetic triplet can be obtained by study thermal decomposition kinetic in a solid state reaction. In the present work, the non-isothermal differential thermal analysis (DTA) was used to study of kinetic triplet of thermal decomposition of Acfol explosive with composition of 5% wax and 95% HMX explosive. The DTA thermograms of Acfol were investigated in heating rates of 2, 4, 6 and 8 ° C per minute in an argon atmosphere. The model-free methods of Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) were used for calculation of activation energy. The average of activation energy was obtained 214.17±25.22 and 233.45±4.63 kJ/mol by KAS and OFW methods respectively in the range of conversion fraction (&alpha) of 0.1-0.9. The kinetic triplet of activation energy, Ea, frequency factor (A) and the reaction model (functions of f(&alpha) and g(&alpha)) were also investigated using model-dependent methods. The obtained results were showed the A3 model with functions integral of [-ln(1-a)]1/3 and differential of 3(1-a)[-ln(1-a)]2/3, activation energy of 226-241 kJ/mol and logA of 13.5-15.8 1/s for thermal decomposition of Acfol explosive.