The paper deals with the problem of thermal fatigue cycles phenomenon, which affects the performance of flexible pavement. The purpose of the paper is to extent the knowledge on the rheology of polymer modified bitumen which was affected by cycles of thermal fatigue. The aim of this research is to determine the rheological components and their evolutions under thermal fatigue with freezing - thawing cycles. To represent thermal fatigue cycles phenomenon of polymer modified bitumen in laboratory, both freezer and controlled temperature room were used to produce the real cycles of freeze - thaw of winter season. The results suggest that thermal fatigue cycle is more complicated on rheological behavior of polymer modified bitumen. It is shown that thermal fatigue cycles influenced the behavior of polymer modified bitumen. It is concluded that thermal fatigue cycles reduce the performance of binder and accelerate the degradation of pavement.