The thermal decomposition of some liquid energetic materials such as TEGDN，TMETN，NG，and GAP and some energetic materials that could melt when they are heated such as HMX，RDX，PDADN，DATH and TNT are investigated when they were at liquid state by using the differential scanning calorimetry (DSC) and the pressure differential scanning calorimetry (PDSC).At different pressure，the different changes of the thermolysis enthalpy，ΔH，and the peak temperature of the DSC curve，T_m，are discussed．With pressure increasing，ΔH will increase and T_m will be larger because pressure can restrain the sublimation or volatilization of these energetic materials．The autocatalysis reaction,the second reaction between gaseous products and the competition of the decomposition between backbone and branch are intensified by increasing pressure. T_m of DSC curves of the compounds containing —N₃ will not chang after pressure restrain their sublimation or volatilization and the thermolysis of these compounds shows special laws compared with other energetic materials.