Abstract: Based on the overlapping project of new Foshan-Dongguan Intercity Railway shield tunnel and Guangzhou metro Line 3 open-cut rectangular tunnel, the dynamic response of traffic load generated by metro train in passing through the opencut tunnel to the lining structure of the new tunnel in the lower part is studied, and the dynamic stress of the new tunnel under different traffic loads is discussed. Then, the excitation force function method is used to simulate the metro traffic load, the response characteristics of vibration acceleration, stress and vertical displacement of the lining structure under different traffic loads are studied by taking typical monitoring sections of new shield tunnel in the lower part as the monitoring points. The results show that the worse the track quality condition, the faster the train speed and the greater car-body mass will result in the larger amplitude of the train vibration load. There is an obvious dynamic influence area under the vibration load of metro train; the vertical displacement curve of the new tunnel section forms the shape of "W", and the vertical displacement amplitude at the vault is the largest. With the acceleration of the train speed, the vertical settlement of the new tunnel also increases. Every 30 km/h increase in train operation speed will result in the settlement increase of the tunnel lining structure by 2.66% on average.