Abstract: The dynamic performances of ballastless high-speed railways under moving train loads, such as vibration behaviors and dynamic soil stresses, are two important issues in the design and maintenance of high-speed railways. Based on an established full-scale physical model for slab tracks, a distributed loading system consisting of eight high-performance hydraulic actuators is developed to simulate the moving train loads with the highest speed of 360 km/h. The tests results such as vibration velocity and dynamic soil stress are offered for a better understanding of dynamic behaviors of slab tracks at various train speeds. The vibration velocity of track structure exhibits an approximately linear tendency with the train speed, while it begins to grow faster until the train speed reaches 180 km/h. The roadbed acts as a nice damping layer for vibration reduction. Although the dynamic soil stress at roadbed surface is much lower in ballastless tracks than that in ballasted tracks, it decreases much slowly with the soil depth in ballastless tracks. Meanwhile, the dynamic amplification coefficient of soil stress is found to be related to both the train speed and the soil depth. An improved empirical formula is then proposed to determine the dynamic soil stress of ballastless high-speed railways.