Abstract: Focusing on the vertical vibration issues induced in the superstructure by high-speed rail （HSR） and metro lines running beneath the Changsha Airport Integrated Ground Transportation Center （GTC） and terminal building， this study conducted vibration response analysis and vibration mitigation control research. A coupled train-track-subgrade dynamic system model was developed using ABAQUS software. The model employs solid elements to characterize the interactions and connections between key components， accurately simulates the vertical dynamic response generated under moving train loads. It is capable of simulating various typical operational scenarios， including constant-speed， acceleration， and deceleration braking. The derived track excitation loads were utilized for structural vibration analysis. An integrated finite element model of the superstructure-track-foundation system was developed in SAP 2000 software to perform time-history analysis， evaluating the structural vibration response under multiple conditions， such as varying train speeds and multi-train encounters. Considering the distinct characteristics of the metro and HSR underpass zones， two primary vibration mitigation strategies were analyzed： 1） installation of a floating slab track （FST） in the railway bed within the subway influence zone， and 2） implementation of steel spring isolation bearings at the base of the superstructure in the HSR influence zone， specifically within the E-Pier area. The results demonstrated that the FST effectively reduces both the structural peak acceleration and vertical Z-vibration level. With this measure， the vibration comfort levels inside the terminal building and GTC during subway operations meet the relevant code requirements. For the E-Pier area affected by the HSR underpass， the installation of steel spring isolation bearings also ensures compliance with code limits for both peak acceleration and vertical Z-vibration level.