Accelerated aging tests under pre-strain were conducted on HTPB-based composite solid propellant with the goal of investigating the effect of pre-strain aging on its microdamage properties. The tensile fracture morphologies, stress-strain curve and dissipative energy density of propellant samples were analyzed. Results showed that there was no obvious dewetting macroscopically when the pre-strain was less than 9 %, but the pre-strain can still cause microdamage of propellant interface. The microdamage of propellant interface can be characterized by the critical dewetting strain, corresponded to pre-strain by a linear law. The bonding performance between HTPB propellant matrix and solid filler was mainly affected by aging temperature. There was a critical temperature T-C, For the HTPB propellant investigated in this study, the T-C is between 65 degrees C and 70 degrees C. When aging temperature is below T-C, there was no significant decrease in the overall levels of dissipated energy density, but decrease began significantly when the aging temperature is above T-C.