Social stability is a vital basis for China's economy, requiring social stability risk assessment of vital hydrological projects, which is part of major decision. This paper, based on 20 social stability risk factors of vital hydrological projects, establishes a risk evaluation index system, which is weighted by entropy. Extensible material element theory combined with social stability risk assessment is used to construct index classic domain and joint domain. A comprehensive correlation is calculated to form the method in assessing social stability risks of vital hydrological projects based on the case of W channel consolidation. This project has a highest low risk hierarchy correlation, which means it is acceptable in social stability risk if prevention is in place. This method has been proven by the actual facts for its execution and adaptability, offering a new idea for social stability risk assessment of vital hydrological projects and effectively alerting the risks. 