By means of the vehicle-track coupled dynamics theory and the corresponding simulation software TTISIM,the effect of track irregularity wavelength on the dynamic response of the vehicle system was investigated.The sensitive wavelength of track irregularity in high-speed operation was discussed.The analysis results show that the dynamic responses of the vehicle system are larger under the condition that the track irregularity wavelength varies in a certain range when the running speed is 250km/h to 400km/h.The wavelength ranges of track irregularities corresponding to the larger responses of vehicle system vary with different irregularity type or running speed.It is found that the vehicle system dynamic responses are sensitive to track vertical profile irregularity,track alignment irregularity and track cross-level irregularity when their wavelength ranges are 80~160 m,40~120 m and 50~160 m at the speed of 250 km/h to 400 km/h.The sensitive wavelength range of track twist irregularity is 40~100 m under the above mentioned speed conditions.