Abstract: A fatigue testing system for polyester cord/rubber composites was established in this paper. Based on this system, the fatigue properties of unidirectional polyester cord/rubber composites under cyclic loading were assessed and the fatigue life prediction equation of rubber composites was given. The study also examined the effect of strain, frequency and temperature on the damage accumulation process of rubber composites. The results indicated that fatigue lifetime and damage accumulation of rubber composites were strongly influenced by cyclic frequency because of hysteretic loss of the materials. This paper offers a method available for evaluating the fatigue behavior of tires and predicting the fatigue lifetime of tires.