Tidal residual is very important to the transport of water particles, nutrients, plank-ton, etc. in the coastal sea. Eulerian scheme and Lagrangian scheme are two different ways to get thetime averaged residual. Solution of the Bohai Sea's hydrodynamic system using a semi-implicit layer aver-aged numerical model yielded different direction Eulerian and Lagrangian tidal residuals. The latter werestronger than the former in most sea areas. Their different directions produced different circulation patternin some areas. Compared with the Eulerian residual, the Lagrangian residual seemed to be more in accordwith the observation.