The thermal decomposition characteristics of high energy RDX-XLDB propellants with or without catalyst were investigated by means of DSC under different pressures. The results show that the decomposition peak of RDX is the main in the propellant decomposition process and peak temperature shifts to lower temperature with the increase of pressure. The lower the main peak temperature,the high burning rates of the propellant.The main peak temperature of the propel lant with catalysts is lower and,therefore getting higher burning rates.