Based on the minimum free energy method, the energy characteristics of six nitrofurazan compounds, 3-nitrofurazan(NF), 3, 4-dinitrofurazan(DNF), 3-nitrimino-4-nitrofurazan(NNF), 3-nitramino-4-nitrofurazan ammonium salt(ANNF), 3-nitimino-4-nitrofurazan hydrazonium salt(HNNF) and 3-nitramino-4-nitrofurazan hydroxyl ammonium(HANNF), were studied by NASA-CEA software. Effects of the content of nitrofurazan compounds on the energy characteristics of CMDB propellants and effects of pressure on the energy characteristics of nitrofurazan /CMDB propellants were studied. Results show that the specific impulses of HANNF and HNNF monopropellants are 2744.8 N·s·kg^-1 and 2802.2 N·s·kg^-1, respectively, which are obviously higher than that of RDX. Six nitrofurazan compounds make the specific impulse of CMDB propellants increase substantially, in which HNNF and HANNF make the specific impulse of CMDB propellants increase by 74.6 N·s·kg^-1 and 91 N·s·kg^-1 , respectively. The specific impulse for the six propellants increases with the increase of pressure. The order affecting the specific impulse by pressure is DNF>NNF>HANNF>ANNF>HNNF>NF.