In order to analyze the distribution characteristics of the modulus field of semi-rigid asphalt pavement in the time domain and spatial domain and to study the effect of the annual change of the modulus field on the fatigue life of the structural layers, the asphalt layers were subdivided into several sub-layers with a thickness of 1 cm. The modulus field distribution in the asphalt layers was obtained by iterative calculations based on the Odemark method, and the fatigue life correction factors of structural layers were obtained based on the Miner linear fatigue damage model as well as the mechanical responses of the pavement structure under 456 conditions throughout the year. The results show that the modulus field varies significantly with time. At the speed of 70 km/h, the ratio of the annual maximum and minimum values of the modulus at each depth of the asphalt layer reaches 20.1~34.9, and the modulus with the pavement depths are not equal at the same time. The ratio of the modulus at the speed of 120km/h to that at 10 km/h is in the range of 1.12 ~ 2.28, which means that the vehicle speed has a significant effect on the modulus field. The influence of the annual change of the modulus field on the fatigue life of pavement structures should be considered. The fatigue life of the upper base calculated under the standard conditions at 20 ℃ and 10 Hz is conservative, while the fatigue life of the lower base is dangerous. The calculation results under the standard condition should be revised by the fatigue life correction factor when checking the fatigue life of the pavement structures.