Abstract: Under the frost and thaw condition, the damage propagation problem of rock is a complex physical and mechanical process. In this paper, two main tasks are presented by use of damage mechanics and CT technology. Firstly, the authors have studied the damage process of rock under different frost and thaw cycles, and discussed the influence of frost and thaw cycles on the damage propagation and the damage propagation constitutive relation of rock, water content and density. CT values are given to express the experimental phenomena of water migration and transition from water to ice. Secondly, the authors have studied frozen temperature imposing on rock damage and the experimental phenomena are reflected by statistical percentage. Two factors, the volume upheaval of transformation from water to ice and the volume shrink of rock materials when temperature decreases are considered. The experimental results show that the impact of frost and thaw cycles and frozen temperature plays an important role in the damage propagation problem of rock under frost and thaw condition.