The effects of energetic imidazoles lead salt (E-Pb) content and E-Pb-carbon black composite on the combustion performances (burning rate, pressure exponent, combustion flame structure, etc.) for RDX-CMDB propellant were studied. The reasons affecting the combustion behaviors of RDX-CMDB propellant by the energetic catalyst and inert catalyst were analyzed. Results show that the combustion performances of the RDX-CMDB propellant with energetic catalyst are better than those of the RDX CMDB propellant with inert catalyst. The burning rate at 10 MPa increases from 11.74 mm·s^-1 for the propellant without catalyst to 25.36 mm·s^-1 for the propellant with E-Pb catalyst and the burning rate of the propellant increases with increasing the content of energetic catalyst. When the energetic lead salt and carbon black are matched, the catalytic effect of the propellant is better. When the mass ratio of carbon black and energetic lead salt is 1.5:0.25, a burning platform appears over the wide pressure ranging from 4 to 17 MPa and the pressure exponent n is less than 0.25.The effects of energetic lead salt on the combustion flame structure, thickness of dark space, number of bright spots on the combustion surface, etc. for propellant have certain regularities.