To investigate the effect of carbon nanotubes(CNTs) on the combustion properties and mechanical properties of Al-CMDB propellant, the propellant samples were prepared through an absorption-extrusion method. The burning rate of propellants was measured by target line method and the pressure exponent was calculated. The tensile strength and ductility of propellant sample were tested at high, low and normal temperature. The reason of how CNTs effected the combustion performance of Al-CMDB propellant was analyzed by scanning electron microscopy(SEM), flame photo, combustion wave, morphology and element analysis of quenching surface and DSC analysis. The results show that the burning rate of propellant in the range of 6-20 MPa can be increased by adding 0.7% CNTs in Al-CMDB propellant, of which the burning rate at 6 MPa is increased most, which is 4.98 mm·s^-1, and the pressure exponent decreases from 0.57 to 0.45 at 6-20 MPa. CNTs with pipe diameter of 10-20 nm can enhance the tensile strength and ductility of Al-CMDB propellant at high, low and normal temperature. The effect of CNTs on the peak temperature of thermal decomposition of propellant is little but can make the exothermic quantity of propellant decomposition increase.