In order to study combustion characteristics of RDX nitramine propellant furtherly,the burning rate pressure exponents for three RDX nitramine propellants were investigated by closed bomb test and data-treatment in the different range of pressure,and were compared with that of the single base propellant. Results show that the burning rate pressure exponent for single base propellant with loading density 0.2 g·cm^-3, is 0.869 at 50-100 MPa,and 0.926 at 150-217 MPa,and it increases as pressure increasing. But the results are reverse for the RDX nitramine propellants,especialIy for RGD and JMZ nitramine propellants whose buring rate pressure exponent is over 1 under 150 MPa,and below 1 at higher pressure. In addition,the values of burning rate pressure exponent of multi-perforation granular propellants are smaller obviously than that of single′perforation cylinder propellants.