<p>This study systematically investigates the fatigue behavior of composite modified double-base propellant (CMDB) under strain-controlled cyclic loading across a range of temperatures. Fatigue life evolution and mechanical response were quantified through tests conducted at multiple temperatures and maximum strain amplitudes, and the effect of pre-fatigue conditioning on the damage evolution of the propellant was analyzed through pre-fatigue tests. It was found that the fatigue life of the propellant was prolonged with increasing temperature. The stress response of the fatigue vibration process shows an obvious three-stage evolution law, including initial softening, continuous stable development and acceleration stage. Based on damage mechanics and viscoelasticity theory, a three-stage evolution model of fatigue damage of CMDB propellant was established. the predicted theoretical results are in good agreement with the experimental data. This framework effectively describes material damage evolution during fatigue cycling, providing a mechanistic basis for performance assessment and service life prediction in solid rocket propulsion systems.</p>