Thanh Hoa has a 102 km coastline with Northeast to Southwest direction, is the downstream of Ma river basin, and is the place where the river tributaries flow into the sea. Hydrodynamic regime in estuaries and coastal area is not only influenced by the monsoon but also affected by the interaction between the river flow and the sea, thus hydrodynamic regime is very complex. Due to the limited number of hydrological gauging stations, there is not enough data for planning, designing to protect the coastal area. The Mike 21/3 Coupled model has been used in this study to calculate the characteristics of waves, flows in the research areas from deepwater area to coastal and estuarine areas, and also identify the seasonal changes of these characteristics. These results will be the basis for proposing the measures for the coastal protection, prevention of landslides... to serve for sustainable economic development of Thanh Hoa province.