Abstract: A 3D numerical model of Jiaozhou bay tide current was established based on ECOMSED model.In the model, the dynamic boundaries was dealed with dry-wet point method.The verification of the model showed that it could predict the tidal current well in the Jiaozhou bay.The model was then used to simulate the tidal current before and after the forebay reclamation in the Jiaozhou bay.Based on the Lagrangian particle tracking method, the pollutant transports before and after the forebay reclamation in the Jiaozhou bay were simulated by tracking the movement of single particle and particle swarm.By comparing with the trajectories of pollutant before and after the reclamation, the influence rules and scope of the forebay reclamation on pollutant transport in the Jiaozhou bay were analyzed, and some suggestions for the arrangement of sewage outlet in the Jiaozhou bay area were provided based on these.