As the most essential factors affecting sustainable regional development, energy and water resources are closely related. Based on the three-scale energy intensity database, this study calculates the whole life cycle performance of a 25,000 tons/day desalination project in Hebei Province, China by combining life cycle analysis with input-output analysis. Considering the embodied energy consumption in different time periods, the corresponding freshwater production per year is 9.13 million m3, and the total energy consumption covering the construction and operation stages is 39.46 PJ, with the energy consumption per year of 1.94 PJ. Considering the embodied energy consumption in different scales and components, the energy consumption at the national scale contributes the largest proportion (68.79%), and the evaporator is the main component in the construction stage (34.30%). For energy consumption in water production, the energy-water nexus index in the project is 18.02 kWh/m3, among which the thermal power could be replaced through the combination of seawater desalination and thermal power plants. Through the reasonable selection of key materials and components and location of seawater desalination projects, the balance between the supply and demand of energy consumption and water production could be optimized from the energy-water nexus perspective.