Thermal decomposition characteristics of five emulsion explosives were studied by DSC-TG at the heating rates of 2.0, 2.5, 7.5, 10 K·min^-1, and the thermal decomposition mechanisms were deduced by means of model-free function of Ozawa method and Costs-Redfern method and ?atava-?esták method. Results show that the activation energies calculated by the three methods are approximate, and the rationalities of thermal decomposition kinetic parameters of five emulsion explosives are verified so as to deduce the most possible mechanism functions of thermal decomposition characteristic of emulsion explosives. For sample 1, it is random nucleation and lateral overgrowth mechanism, for samples 2 or 5, it is Mample Power pricnciple n=2/3 mechanism, for samples 3 or 4, it is three dimension diffuse, 3D mechanism.