In order to understand the influence of damage on the life of rocket motor, the damage and failure behavior of HTPB propellant was studied, and the methods to characterization of damage properties and the ability of propellant anti-damage were studied too. The influence of environment and stress on propellant damage was discussed. It is found that HTPB propellants have different anti-damage properties, depending on the dewetting point stain (ε_d). The damages in the propellant can be characterized by E_5%, dewetting energy, permanent stain, and S-shape curve of propellant. The environment humidity affects the damage properties of propellants significantly.