Abstract: Consider the rail vehicle dynamic models with uncertain parameters and nonlinear uncertainties. Using the Lyapunov stability theory and employing the special properties of matrices, a lateral stability criterion for the system is derived. The robust stability bounds obtained are not necessarily symmetric with respect to the origin in the parameter space, and can significantly enlarge the stability region for the uncertain parameters. The robust stability of a rail vehicle wheelset subjected to uncertain suspension is analyzed by using the proposed approach, and the results obtained in this paper are compared with existing ones.