Based on the characteristics of seawall failure, main factors threatening seawall safety are summarized in terms of the two forms of failure, overtopping and breaches. An index system for seawall safety assessment was established based on the analytic hierarchy process(AHP). Based on features of seawall design in China, the membership degree method from fuzzy mathematics was used to quantify every index according to the Code for Design of Sea Dike Project(SL 435—2008). The index system for seawall safety assessment was applied to a seawall in Taizhou, in Zhejiang Province, in order to assess the risks of overtopping and breaches. The results show that this seawall meets the design requirements for a return period of 50 years. The established index system for seawall safety assessment can be used to investigate the risks of overtopping and breaches of other seawalls.