Four series of TNT based melt cast explosives were prepared by mixing RDX, CL-20, FOX-7, and TKX-50 with TNT in different mass ratios. The compatibility of these composition explosives was evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) according to the STANAG 4147 standard. Furthermore, the DSC and TGA data were also used to calculate the activation energies by the Kissinger and Ozawa methods. The experimental results indicated that the TNT/FOX-7 composition explosives had good compatibility, whereas the TNT/CL-20 composition explosives had poor compatibility. The TNT/RDX and TNT/TKX-50 composition explosives at the mass ratios of 50 : 50, 40 : 60, 30 : 70, 20 : 80 and 10 : 90 had good compatibility. Furthermore, the decomposition activation energy of TNT/FOX-7 composition explosives increased with increasing FOX-7 content. Under the compatible condition, the decomposition activation energy of TNT/RDX composition explosives also increased with increasing RDX content, but the decomposition activation energy of TNT/TKX-50 composition explosives decreased with increasing TKX-50 content.