The thermal analysis characteristics and their relationship with burning rate at various pressures for five RDX-CMDB propellants were investigated by high pressure Differential Scanning Calorimetry （DSC）. The results show that PDSC characteristics of the propellants are affected obviously by pressure and catalyst,and the first and second decomposition peak temperatures all drop with pressure increase for five propellants,the ratio of decomposition heat ΔH_d to ΔT which is the difference of onset and end decomposition temperature all increases as pressure increase,and it can better presents the influence of pressure on thermal decompositions of RDX-CMDB propellants. A relationship of ΔH_d/ΔT with burning rate at various pressures appears in these propellants.