In order to improve the safety of ammunition, the effect of TATB content on the heat transfer and response properties of cast explosive during the roasting was studied. The 3D-Fluent software was used to simulate the roasting process of cast explosive. The response time and temperature of explosive with different TATB content were predicted, and the accuracy of the simulation was verified by the cook-off test. The results showed that the gradient temperature and response properties of the explosive were closely related to the heat transfer coefficient of the medium. The increase of TATB content could improve the thermal safety of explosive by changing the response temperature and time under the roasting condition. Moreover, the reliability of predicting explosive’s response temperature and time by the method of simulation calculation was good.