The invention belongs to the technical field of vibration and noise reduction of rail transit, A floating slab ballast bed for isolating vibrations generated during operation of a rail vehicle is disclosed, comprising a floating plate and an elastic vibration isolation device, the elastic vibration isolation device is placed in an installation reserved space or a coupling sleeve arranged on the floating plate, The elastic vibration isolation device includes an upper housing, a lower housing, and an elastic element disposed between the upper housing and the lower housing, the elastic element including a static support spring and a combined support spring. As that system frequency of the float slab ballast bed with weak correlation between the frequency and the load does not change obviouslywith the change of the load, the correlation between the system frequency and the load is weak, and the float slab ballast bed has the characteristics of simple structure, strong adaptability to dynamic load variation, good vibration isolation performance and the like, and can be widely applied to vibration isolation engineering of various rail transit.