Fused cast explosive will melt in the process of cook-off, which will affect the thermal reaction of the explosive.In this paper, the cook-off bomb test of carrier explosive 2, 4-dinitroanisole(DNAN) was carried out to measure the temperature change in the explosive center point and observe the melting and reaction situation of explosive.A thermal reaction model of fused cast explosive was established.The melting process of explosive was calculated and analyzed by an enthalpy-porosity method.The autothermic reaction process, thermal conduction, convection after explosive melting and radiation heat transfer of air were considered.The numerical simulations of the explosive cook-off test was performed.Compared with the experimental results, the accuracy of the calculation was verified.The activation energy and pre-exponential(frequency) factor of DNAN explosive were 172 kJ·mol^-1 and 1.20×10¹¹ s^-1, respectively.The cook-off characteristics of DNAN were calculated and analyzed at six kinds of heating rates of 3.3 K·h^-1, 0.3 K·min^-1, 1.0 K·min^-1, 3.0 K·min^-1, 10 K·min^-1 and 60 K·min^-1.The explosive at slow heating rate completely melted before ignition.And the explosive at relativly fast heating rate ignited on the edge, while the explosive inside not completely melted.The images of temperature distribution and liquid phase fraction distribution of ignition time were obtained.Results show that in the cook-off of fused cast explosive, the state of the explosive before ignition will be affected by heating rates, and the intensity of explosive thermal reaction will be affected by that.