为研究轨道结构敏感因素对中长波高低不平顺的影响，建立了车辆-轨道耦合模型，基于惯性基准法仿真检测轨道高低不平顺，分析了轨道结构振动及不同扣件刚度、路基支承刚度和轨枕间距对高低不平顺的影响。结果表明：在波长2~6m范围内，柔性轨道估算不平顺明显大于无质量轨道不平顺；从时域角度分析时，扣件刚度、路基支承刚度和轨枕间距对高低不平顺影响较小，而从频谱角度分析时，轨道谱变化明显且主要影响波长2~4m、2~10m、2~3m范围内的高低不平顺。因此，分析轨道不平顺的分布特征及其发展变化规律时，应结合幅值和轨道谱角度综合分析。

In order to study the influence of track structure sensitive factors on medium and long wave longitudinal irregularity, a vehicle track coupling model is established. Based on inertial reference method, the track longitudinal irregularity is simulated and detected, and the influence of track structure vibration and different fastener stiffness, subgrade support stiffness and sleeper spacing on the longitudinal irregularity is analyzed.The results show that the estimated irregularity of flexible track is significantly larger than that of massless track in the wavelength range of 2~6m; From the perspective of time domain, the fastener stiffness, subgrade support stiffness and sleeper spacing have little influence on the longitudinal irregularity, while from the perspective of frequency spectrum, the track spectrum changes obviously and mainly affects the longitudinal irregularity in the wavelength range of 2~4m, 2~10m and 2~3m.Therefore, the analysis of the distribution characteristics and development of track irregularity should be combined with amplitude and track spectrum angle.