To understand the effects of slow heating on the safety of explosive components, the differential scanning calorimeter (DSC) analyses of powder PBX-6 explosives under various pressures and heating rates were conducted, and accelerated aging tests of SR50 mm hemispherical PBX-6 explosive components under 55 ℃ for 140 days were carried out. The device was designed for the slow cook-off tests of Φ100 mm explosive sphere, and the slow cook-off tests at heating rates of 2 ℃·min^-1 and 5 ℃·min^-1 were carried out for spherical specimens S-1^# and S-2^#, respectively. Through analysis of the temperature history at measuring positions recorded by thermoelectric couples and temperature measuring system, combined with the comparison of the shock wave overpressure and the residues after deflagration, the relations between the slow cook-off behaviors and the thermal decomposition characteristics were studied, and the safety of PBX-6 explosive components under slow heating conditions was evaluated. The experimental results show that the specimen S-1^# moderately deflagrates after heating 8373 s with deflagration temperature of 218.5 ℃ at heating rate of 2 ℃·min^-1, and the specimen S-2^# violently deflagrates after heating 4074 s with deflagration temperature of 224.9 ℃ at heating rate of 5 ℃·min^-1 and the shock wave overpressure is 21.8 kPa. It indicates that, as the heating rate rises, the explosive components will deflagrate with shorter heating time, higher deflagration temperature and a higher grade of deflagration.