In this study, the dynamic modulus master curves and time-temperature shift factors of asphalt mixtures were incorporated in finite element method to take into account the effects of the load frequency and temperature on the mechanical properties of asphalt mixtures. Bottom-up fatigue cracking of a typical asphalt pavement structure with flexible bases under moving load was analyzed with fracture mechanics. The results showed that one, two or three peaks of tensile type stress intensity factor ( KⅠ) at the crack tip could be induced during one passage of wheel load over the crack under various conditions, while two peaks of shear type stress intensity factor (KⅡ) always occurred，which were equal in magnitude but had opposite directions. The effects of temperature, vehicle speed and crack length on stress intensity factor and its frequency were analyzed. It was found that crack propagation was mainly controlled by KⅠ for pavements with short crack length and at low temperature, and KⅡ gradually became the main driving force for crack propagation as temperature and crack length increased.