Based on the refined threedimensional modeling method, a coupled vibration FEA(finite element analysis) model was established for light railway train and long span twolayer cablestayed bridge with the consideration of the material and geometry nonlinearity and over 2.2 million of element and nodes.To overcome the computing difficulty for large number of element, the solution was carried out with the Dawning 4000A supercomputer in Shanghai Supercomputer Center based on Contact Balance Bisection Algorithm for parallel computing.Through the simulation of one way and two way conditions, the key component's stress of cablestayed bridge girders and dynamic response of middle span section was respectively analyzed.