【Objectives】The existing prediction formula of vibration source intensity is only applicable to normal-speed subways, and cannot be applied to the vibration source intensity characteristics of fast underground lines with a maximum speed of 160 km/h.【Method】The vibration characteristics of multiple sections of a coastal city urban expressway were measured on site. The influence of vehicle speed, tunnel buried depth, curve and other factors on the vibration source strength was studied through data analysis.【Result】The vibration source intensity was between 71 dB and 80 dB at the speed of 90 km/h to 160 km/h in the straight (curve) line section. The vibration source intensity also increased with the increase of vehicle speed,and the vibration source intensity increased by 3.72 dB for every 20 km/h increase in speed. The vibration source intensity decreases with the increase of the buried depth of the tunnel. For every 10 m increase in the buried depth of the tunnel, the vibration source intensity decreases by 4.9 dB. In the same case, the vibration source intensity of the curve section (curve radius 1 850 m) is stronger than that of the straight section, and the value is about 7 dB. One year after the train was put into operation, due to the deterioration of the wheel-rail state, the vibration source intensity increased, and the difference between different trains was large. The monitoring data of seven months of a certain section were selected and analyzed. The vibration source intensity was relatively stable after the operation period was stable.【Conclusion】The vibration source intensity of the fast underground line is affected by many factors: it is linearly positively correlated with the train speed, the tunnel depth is linearly negatively correlated, the vibration source at the curve is stronger than that at the straight line, and the wheel-rail deterioration will also increase the vibration source intensity.