Abstract. Fiber-optic sensors are widely used in the long-term health monitoring of major engineering structures, and it will generate heat fatigue damage under the influence of the environment, which greatly affect the stability of the optical fiber sensor. In this paper, experimental analysis for optical properties and thermal fatigue damage were studied. Based on the experimental data, the thermal expansion coefficient of the fiber is approximately . Points out at temperature cycling conditions, the fiber damage occurred, the elastic modulus exhibits decreasing trend. Analysis of the mechanism of fiber thermal fatigue damage and the impact on performance of the optical fiber sensor .The results of this research provide a reference to predict the durability and life of fiber optic sensors.