Abstract: Due to its high energy and safety characteristics, 3,4-dinitropyrazole (DNP)-based melt-cast explosives hold great promise in the field of energetic materials. Studying the thermal safety of these explosives is crucial to provide theoretical and experimental support for their engineering applications. To explore the thermal response characteristics of DNP-based melt-cast explosives, experimental cook-off tests were conducted to monitor their internal temperature variations of projectiles with dimensions of \phi 60 mm×240 mm under a heating rate of 60 °C/h. Additionally, a numerical simulation model of the cook-off test was established using Fluent software. Upon validating the simulation method, the evolution of temperature field over time during the cook-off process was analyzed, and further investigations were conducted on the effects of heating rate and projectile placement on the simulation results. The results indicate that the response of the cook-off test is characterized by deflagration. The deviation between experimental response parameters and simulation results is within 5%, preliminarily verifying the reliability of the numerical model. The heating rate significantly affects the response time, temperature, and area of the cook-off projectile, while the placement method mainly influences the distribution of its response area.