Huong river basin has rich water resources, it plays a very important role in social and economical development of Thua Thien Hue province and also in environmental protection. The natural conditions of Huong basin has natures of all basin belongs to Thua Thien Hue province with large lagoon system Tam Giang - Cau Hai and very low tidal regime. In recent years, on Huong basin there are hydropower and irrigation reservoirs has been build such as Binh Dien, Co Bi, Ta Trach. These structures will effect on the flow regime at downstream of Huong river. In this study, two hydrological and hydraulic models HEC-HMS and HEC-RAS have been applied to simulate the river flood flows. The results shown that these models can be used for the next steps to assess the effect of reservoirs in upstream on the flow regime of downstream of Huong river.