In order to study the reasonable mechanical parameters of the shear hinge of the prefabricated short steel spring floating slab track（FST），the vertical coupling dynamics model of the train-floating slab track（T-FST）is established by rigid body dynamics and finite element（FE）direct stiffness method and the shear hinge is simulated by bending and shear spring elements. The influence of shear hinge stiffness，prefabricated slab length and steel spring stiffness on the dynamic response of the T-FST coupling system are calculated and analyzed. The results show that compared with the cast-in-place long slab，when the prefabricated short slab is not provided with shear hinges at the joints，the rigidity of the end of the slab is not continuous，the vibration of the track structure is intensified and the force of the end of the slab and the force of the steel spring are increased，which makes the fastener broken and vibration reduction of the FST reduced. The shear joint is installed at the joint of the prefabricated short slab，which will improve the integrity of the track and vibration reduction efficiency. When bending stiffness and shear stiffness of the shear hinge are 1×108（N?m/rad）and 1×108 N/m，the connection performance can achieve ideal results. The length of the prefabricated slab has no significant effect on the mechanical parameters of the shear hinge. The smaller the stiffness of the steel spring，the higher the bending and shear stiffness requirements of the shear hinge.