To investigate the cook-off response characteristics of JEO explosive （NTO/HMX/additives）， an experimental system for multi-point temperature and pressure measurements during the cook-off process of explosive was devised. The cook-off experiments of JEO explosive were conducted at two different heating rates of 5 ℃·min^-1 and 2 ℃·min^-1 to obtain the ignition time， ignition temperature， temperature history at different positions within the explosive， and pressure evolution inside the device. The effect of heating rates on temperature and pressure variations and reaction intensity during the cook-off process of JEO explosive was analyzed. Furthermore， based on the experimental research， a multiphase flow species transport model for explosive cook-off was adopted considering the influence of pressures on the thermal decomposition reaction of explosive， and numerical simulations were conducted to investigate the thermal decomposition process of JEO explosive under different heating rates using Fluent software. The results indicate that the thermal decomposition reaction of JEO explosive proceeds slowly before phase transition， while it accelerates significantly afterwards， leading to a rapid increase in temperature and an exponential growth in pressure until ignition. The ignition temperature of JEO explosive is approximately 220 ℃， and its response level is deflagration under the constraint conditions of this experiment， demonstrating excellent thermal safety. As the heating rate decreases， the ignition time of JEO explosive prolongs， and the ignition location shifts from the edge of the charge towards the center， resulting in an increased intensity of the reaction. During the thermal decomposition process before ignition， only a small portion of the explosive undergoes reaction， with the majority of the reaction occurring during the combustion stage after ignition.