Long-term transport processes in coastal seas with time scales from weeks to seasons time scale are controlled by residualcirculation. In the Bohai Sea, an ultrashallow shelf sea of China, tidal residual is almost the dominant factor to the circulationdue to slight stratification and weak wind in summer. In order to establish an adequate hydrodynamic base to the ecosystemdynamics of the Bohai Sea, the differences of tide-induced Lagrangian and Eulerian mean circulation are discussed andcalculated in this contribution. The Stokes drift is analyzed theoretically. According to Longuet-Higgins [Deep-Sea Res. 16 (1969) 431], the Lagrangian flow is the sum of the Eulerian flow and the Stokes drift that is induced by the mean kinetic energyand coastal nonlinear interaction. Stokes drift is large in the coastal sea and in areas where the vorticity and/or divergence arelarge. Vertical mass transports by Stokes drift are also the result of nonlinear interaction of current, water level and topography.Hamburg Shelf Ocean Model (HAMSOM) is applied in the Bohai Sea to simulate the tides and tidal currents. The tide-inducedLagrangian mean circulation and the Eulerian one are calculated at the same time. In the area where the Stokes drift is in thesame direction as the Eulerian residual, the Lagrangian one is stronger than the Eulerian one. Where they are pointing inopposite directions, the Lagrangian one is small, like in the southwest of the Bohai Bay, Liaodong Bay and Bohai Strait. TheLagrangian residual current flows into the Bohai Bay along its southern bank causing deposition of Huanghe River sediments.This is in agreement with observations.