The solidification process is a crucial stage in melt cast explosive manufacturing that significantly impacts charge quality. This study presents a finite element simulation of the water-bath solidification process for a TNT-based explosive charge, incorporating thermal air insulation to optimize solidification behavior. The improved process accelerates lower charge solidification while maintaining open feeding channels longer, resulting in a 41.81 cm3 reduction in shrinkage cavity volume compared to conventional methods. A systematic investigation of key parameters - including water-bath elevation rate (0.02–0.2 mm/s), bath temperature (25–60 °C), and thermal air temperature (80–100 °C) - reveals their significant effects on shrinkage defect formation. These findings provide valuable guidance for enhancing the quality and reliability of melt-cast explosive charges through optimized solidification control.