Femtosecond laser can ablate explosives to generate a high-temperature, high-pressure plasma in extremely short time. The femtosecond laser can be used to precisely process energetic materials or assemblies containing energetic materials. Deep understanding of the thermal effects within the explosives during femtosecond laser ablation is the basis for the development of the safe processing technology of explosives using femtosecond laser. A fluid-solid coupling calculation model of single-pulse femtosecond laser ablation of explosives was established to study the combined thermal effect of the thermal radiation of the plasma and the autothermal reaction of the explosives. The hydrodynamic process of femtosecond laser ablation on TNT was calculated. The results show that in the unablated zones of the explosive, significant thermal effect was detected, and the peak temperature is higher than that of ignition. Due to the small zones affected by the thermal effect and its extremely short duration time, the temperature in the explosive drops quickly, thus the explosive is not ignited.