RDX-CMDB propellants containing guanidinium azotetrazolate(GZT) were prepared by standard cast technique. Properties including energy, combustion, thermal security and the thermal behaviors of RDX-CMDB propellants were studied through theoretical calculations and experimentations. Results indicate that the specific impulse(I_sp), explosion heat(Q) and adiabatic combustion temperature of RDX-CMDB propellants decrease with the replacement of RDX by GZT, and gas volume increases. Replacement of RDX with 15% GZT makes the specific impulse, explosion heat and adiabatic combustion temperature decrease 29.2 s, 1248 kJ·kg^-1 and 800 K, respectively, and gas output increase 10.73 mol·kg^-1. GZT makes RDX-CMDB propellants detonate and deflagrate more easily at high temperature above 200 ℃, but has no obvious influence on thermal security of RDX-CMDB propellants below 100 ℃. For RDX-CMDB propellants without the catalysts(lead and copper composite organic salts), GZT could increase the burning rates and decrease the pressure exponents of propellants, 15% replacement of RDX by GZT results in the increase of burning rate by 1 mm·s^-1 under 7 MPa and the decrease of pressure exponent from 0.86 to 0.70 under pressure 7-10 MPa. For RDX-CMDB propellants with the catalyst, GZT decreases the burning rates and increases the pressure exponents of propellants, 15% replacement of RDX by GZT increases the pressure exponent from 0.47 to 0.69 under pressure 7-10 MPa and decrease the burning rate by 3 mm·s^-1. The TG experiments of RDX-CMDB propellants containing GZT indicate that a mass loss process corresponding to decomposition of GZT appears in the TG curve.