To research the ignition and combustion characteristics of base bleed propellant in the base bleed unit and improve the accuracy of numerical simulation, the specific heat capacity and conductivity coefficient for unaged and naturally aged (stored in a sealed plastic bag under room temperature) AP/HTPB base bleed propellant used in a 155mm base bleed projectile were determined by differential scanning calorimeter (DSC) and conductometer, respectively. Results show that the maximum endothermic peak temperature and the maximum exothermlic peak temperature on DSC curve of the aged base bleed propellant at a heating rate of 20 ℃·min^-1 are 253.52 ℃ and 437.54 ℃, respectively. The function of specific heat capacity as temperature with in 40-180 ℃ is obtained based on DSC curves by polynomial fitting method. The average specific heat capacity and conductivity coefficient are 0.9868 kJ·kg^-1·℃^-1 and 0.2292 W·m^-1·K^-1 for the aged base bleed propellant and 0.8887 kJ·kg^-1·℃^-1and 0.4020 W·m^-1·K^-1 for unaged base bleed propellant, respectively. In comparison with unaged base bleed propellant, the average specific heat capacity of aged base bleed propellant increases about 11%, whereas conductivity coefficient of aged bleed propellant decreases about 43%.