The thermal decomposition of RDX-CMDB propellants with burning rate catalysts ［lead-gallate (GDPB), Cu(Ⅱ)-p-aminobenzoic acid (PAC) and carbon black (CB)］ was investigated by pressure differential scanning calorimetry (PDSC). The effect of nano and un-nano catalysts on its thermal decomposition was compared. Results show that the pressure and the burning rate catalysts with different components affect the characteristic values of PDSC and the relative releasing heat of RDX. The characteristic values of PDSC（≤14 MPa）and pressure can be correlated to burning rate using an empiric equation by binary regression. The equation includes parameters that show the contributions of pressure and exothermic rate to burning rate. At high pressures (8-14 MPa), the plateau effect of propellants and the effect of composite catalysts with different components on burning rate can be described by this equation too.