To improve the performance of the propellant，energy properties,mechanical properties and combustion properties of HTPB propellants were studied. The results show that the theoretical specific impulse is enhanced with the increasing of solid contents,and reaches 270.62 s when the solid contents are 90% (including AP 37%,RDX 36.6%,Al 17.4%). The pressure exponent of 90% solid contents HTPB propellant (including AP 43%,RDX 30%,Al 17%) is about 0.34 and ε_m reaches 50% at -40 ℃. By modifying the different contents and particle size distributions of AP or RDX,the burning rate of 88% solid contents HTPB propellant (including AP 48%,RDX 23%,Al 17%) is enhanced from 7.0 mm·s^－1 to 10.9 mm·s^－1,and the pressure exponent is about 0.4, and ε_m reaches 74% at 20 ℃.