A coupled model of a double-line subway train-track-foundation soil was established on the basis of 2.5D FEM to study the vibration isolation effect of the isolation trench during double-line subway operation.The model addresses the problems introduced by the simplification of track structures into an Euler beam on an elastic foundation and introduces the dynamic parameters of the actual rail.The model was used to analyze the vibration isolation effect of the isolation trench on the surrounding foundation under double-line subway train load.The vibration damping characteristics of open and in-filled trenches were compared, and the trench factors that influence isolation were systematically analyzed.Results showed that under the double-line subway load, the in-filled trench had better isolation and engineering practicality than the open trench.The in-filled trench can exert a good damping effect even with a reduced ditch depth.In addition, the isolation effect can be improved by increasing the depth and width of the in-filled trench.The results of the present work can provide useful reference for the vibration isolation design and construction of double-line subways in the future.