To study the thermal response of two new DNAN-based aluminized explosives RB-2X（DNAN/HMX/Al/binder） and RM-2X（DNAN/HMX/NTO/Al/binder）， small-scale cook-off experiments and simulations of RB-2X at a heating rate of 1.0 K·min^-1 and RB-2X at heating rates of 1.0 K·min^-1 and 0.5 K·min^-1 were conducted. The numerical simulation used multi-component grid cell calculation method and considered the air gap formed by cooling and contraction of fused cast explosive. The thermal response of explosives were analyzed. The comparisons of ignition time between simulation and experiment show that the ignition time deviation of RB-2X explosive is 1.13%， and the maximum deviation of RM-2X explosive is 5.63%. The influence of the air gap between the explosive and the inner wall of the bomb on ignition time was also analyzed. The results show that the delay time increases gradually with the increase of gap width， and when the air gap expands to 0.75 mm， the delay time is stable at 90 s， indicating that the air gap has a significant influence on the explosive ignition time. The thermal response of large-scale cook-off bomb with RM-2X explosive was predicted. The results show that the temperature at center point can be significantly reduced at ignition by increasing of ammunition size and heating rate. The state of DNAN changes from total melting to solid-liquid coexistence.