This paper presents an application of a well-calibrated and integrated hydro-economic model representing all River Nile System within Sudan. The aim of this study is to assess the economic impacts of Grand Renaissance Ethiopian Dam (GERD) on hydropower generation for the existing Sudan Hydro-power plants. Recent research has demonstrated that multidimensional and multi-scalar hydrological changes are going to occur after GERD 1st filling and definitely in the long term operation. This raised issues assuring the need to develop integrated tools to be used for the analysis of impacts and to develop adaptation measures, furthermore understanding the system behavior and response. A detailed hydro-economic model is developed to support multi-objectives water resources assessments for the Sudan. The model provides integrated assessment of both hydrological and economic impacts of changes in water resources due to GERD operation. Initially, features of Nile System within Sudan were modeled using RiverWare software. In addition to that, constraints, reservoir operation policy and hydrology were supplied to the model. Economic analysis were performed to evaluate the results and to weigh the outcomes from financial point of view for different scenarios compared to the baseline. It worth mentioning that, GERD is going to negatively affect hydropower generation in Sudan during the first reservoir filling, while positively increasing the opportunities to maximize hydro-generation by considerable amount if new operation policies are adopted.