In order to ensure the safety of steel spring floating plate during service period, two adjacent curve sections of steel spring floating plate track of a new subway line were arranged at the same time to test the transverse displacements of rail and floating plate at different speeds, and a dynamic simulation model was established to simulate the most unfavorable working conditions. The test and simulation results show that the transverse displacement of rail and floating plate is not affected by the change of speed, but the transverse displacement of rail and floating plate increases with the decrease of curve radius. When the line is put into use, the increase of the train load and the deterioration of the irregularity of the line lead to the increase of the transverse force between the wheel and rail, which causes the increase of the transverse displacement of the rail and the floating plate.