Using a self-designing fast cook-off set-up,the response of 2，4，6-trinitrotoluene (TNT) explosive with the thickness of 2,4,6 mm confinement were tested, and the influence of thickness on the TNT explosive cook-off characteristics were studied using the pressure differential scanning calorimetry (PDSC) teconology. Results show explosives exploded with different confinement. With the pressure increasing the decomposition temperature of TNT increased, which shows its reaction rate and energy release increased. Therefore, PDSC could be used for inspecting the explosive cook-off response.