Abstract: China's coastal areas have characteristics such as complex environments, dense structures, and high seismic hazard. Structures located in China's coastal areas are subjected to the coupling effect of chloride corrosion and wind fatigue for a long time, which increases the risk of collapse and economic loss to structures under seismic excitation. Previous studies had shown that the coupling effect can accelerate the degradation in mechanical properties of materials. Where the degradation of mechanical properties can be quantified by the coupled damage of corrosion and fatigue, but previous coupled damage studies were mostly focused on one-way coupling analysis. Less attention to the interaction between the corrosion and fatigue, which results in a great error in the estimation of the remaining mechanical properties of the material, reducing the credibility of the risk assessment for coastal structures under the consideration of the interaction of corrosion and fatigue coupling. The study constructs a damage calculation model based on corrosion rate and fatigue damage parameters when the interaction between the corrosion and fatigue are coupled, and proposes the solution method of the model to realize the quantification of damage and risk assessment of coastal structures. To construct the interaction model, a multivariate interaction model in mathematics was introduced and corrosion rate and fatigue damage were embedded in it. To make the interaction model have the physical meaning that coupled chloride corrosion and wind fatigue are accelerated with time, the time-varying accelerated coupling factor β(t) was proposed to modify the interaction model. Bayesian inference was used to establish the probability distribution of β(t) for the solution. Taking a coastal towering structure as an example, the analysis reveals that the interactive coupling effect can greatly increase the structural risk, also demonstrates the feasibility and applicability of the method proposed.