The dynamic modulus of semi-rigid material is one of the important material parameters widely used in the design and evaluate of asphalt pavement, which has a great effect on the reliability, healthy condition and service life of pavement. To show the three-phase degradation process of dynamic modulus accurately and calculate the time-dependent reliability based on fatigue damage, the degradation models based on non-linear fatigue damage and improved Wei-bull distribution modulus degradation are established and testified in this paper, considering the threshold of normalized modulus. Then the reliability models based on the two above degradation process models are evaluated. Finally, the reliability analysis procedure is established using Monte Carlo (MC) method and the corresponding calculation is conducted using Matlab. Cement stabilized macadam is used as an example in this paper. Results show that non-linear fatigue damage and improved Wei-bull distribution modulus degradation models can indicate threephase degradation process of semi-rigid material modulus better and the reliability based on the proposed two models was more accurate to the actual situation.