The Vu Gia - Thu Bon river basin is facing many problems related to ensuring water security in the basin. In recent years, due to the impact of socio-economic development activities, the impact of climate change with the manifestations of saline intrusion, changes in the rainfall regime, etc. The transfer of water from the Vu Gia river to the Thu Bon river when Dak Mi 4 Hydropower Plant came into operation has greatly affected the assurance of supply for water needs, especially in the downstream area. Three methods are used in this paper such as statistical analysis, PAM (process analysis method), and SMART to build a framework for water security assessment for the Vu Gia - Thu Bon river basin. The proposed results are evaluated by the Framework with 5 key dimensions, 17 main indicators with 28 specific variables. Consequently, it is possible to calculate the aggregate water security index for each specific area, helping decision-making and policy making to improve the water security level for the basin in the context of climate change and socio-economic development.