The energy, combustion and combustion residues properties of composite modified double-base (CMDB)propellants with CL-20 were compared to those propellants with RDX. The energy characteristic of CL-20/RDX-CMDB propellants had also been calculated theoretically based on the principle of minimum free energy. The energy property of propellants with CL-20 was found to be evidently enhanced in comparison to those propellants containing RDX. The findings on combustion properties revealed that the combustion properties of CL-20-CMDB propellants were contrary to the of RDX-CMDB propellants. With the mass fraction of CL-20 increasing in the propellants, the burning rates of propellants can be enhanced significantly, but the burning rates of propellants containing RDX decreased. Analysis of the combustion residues for CL-20/RDX-CMDB propellants revealed that the C, Cu and Pb elements aggregated on combustion surface, which may be useful for guiding the regulation of combustion performance of high-performance CMDB propellants containing CL-20.