Abstract: Based on data of waves, tidal currents and grain size parameters of seafloor surficial sediments measured at the Dongying Harbor area in October 2008,spatial distribution pattern and grain size trend of seafloor sediments were analyzed. The analysis results show that main type of seafloor sediments at Dongying harbor area is clayey silt, the grain size distribution pattern of which is coarse-fine-coarse-fine from coast to sea.These sediments are transported from the coarse-particle zones to the fine-particle zones. The approach embankment and approach bridge obstruct the propagation of tidal currents and waves, and a convergent or divergent flow is formed at the joint part of them.Variation of the local flow field leads to different sediment distributions and transportation patterns between the south and north zones of the approach embankment. A further study shows that transportation of the seafloor sediments is from coast to sea, which is similar to the residual current in direction.