In　this　paper,　a　new　mechanics　model　of　the　in-plane　vibration　for　train-track　coupled　system　is　proposed　to　analyze　the　nonlinear　dynamics　of　train-track　interaction　in　the　case　of　high　speed.　According　to　the　stress　analysis　and　using　Hamilton　principle,　we　obtain　the　governing　equation　of　motion　for　the　train-track　coupled　system.　The　method　of　multiple　scales　and　the　Galerkin　method　are　directly　used　to　the　governing　nonlinear　equation　and　to　obtain　the　nonlinear　averaged　equation.　Based　on　the　averaged　equation,　we　give　numerical　simulations　and　find　period　response　and　chaotic　response.