In order to understand the change of mechanical properties and damage mechanism of HTPB propellant, the influence of strain rate and loading on tensile properties of HTPB propellant was studied by means of uniaxial tension. The dissipated characteristics under mechanical loading was analyzed based on dissipated energy model. Results show that the mechanical properties and the dissipated energy of HTPB propellant were distinctly influenced by strain rate and by different control of strain. Tensile strength, elongation and dissipated energy increased linearly with the logarithm of strain rate. The results can be used as reference to research on properties of HTPB propellant in storage and use.