The main factors influencing on detonation heat of explosives are researched in this paper through analysis of the test data. It has been indicated that charge density,material and thickness of the charge shell are the main exterior factors,while the essence is the influence on the transfer of the chemical equilibrium resulting from the pressure of products at the ' freeze out' temperature. It has also been pointed out that the detonation heat is the mutual coupling result of the chemical property and the applica-tion conditions ( charge density,shell,etc) .