本文应用车辆－轨道系统用合动力学理论，对车辆经过一段由缓－圆－缓组成的线路进行了车辆的脱轨稳定性分析。通过对车辆在耦合动力学模型与传统车辆动力学模型下脱轨稳定性之分析比较，指出了进行车辆脱软的耦合动力学分析的必要性。 In this paper, based on the theory of combined dynamics of vehicle-track system, the derailment stability of the vehicle is analyzed after a period of slow-round-slow train. By analyzing and comparing the derailment stability of the vehicle under the coupling dynamics model and the traditional vehicle dynamics model, the necessity of the coupling dynamics analysis of the vehicle de-softening is pointed out.