With the rapid development of high-speed railways, trains traveling at high speeds induce significant dynamic stress on the track structure and strong vehicle vibrations, directly impacting operational safety and passenger comfort. In this chapter, a track element model, a slab track-bridge element model, and a 15-node, 26-degree-of-freedom vehicle element model are proposed. Using the finite element method and Lagrange’s equation, the stiffness, mass, and damping matrices for both the track and vehicle elements are derived. The train-track-subgrade (or bridge) coupling system is discretized into finite vehicle and track elements, with the track-subgrade (or bridge) system modeled as a series of track elements and the train represented by vehicle elements. During computation, the global stiffness, mass, and damping matrices of the track-subgrade (or bridge) system are generated only once. In subsequent time-step calculations, only the vehicle element matrices need to be assembled into the global matrices of the track-subgrade (or bridge) system. This approach significantly improves computational efficiency.