Research conclusions: The analysis resultsofdynamic response on the slab track show that the criticalvelocitiesexistin the track structure. The dynamic displacements of the rai,l slab and concrete base to track direction become the biggest when train runs at even speed. Meanwhile, peak value of dynamic displacement occurs at different speed and acceleration undervariable speed. The peak value ofdynamic displace stillexists at the differentspeed and acceleration when the train speed slows down, and the dynamic displacement of each structure will reduce at increasing positive acceleration and reducing negative acceleration and vice versa.