The Sanmen Bay is located in an area that is highly vulnerable to typhoon disasters. Sea level rise (SLR) induced by climate change superimposed with storm surges and waves can lead to severe marine disasters. To reduce the losses of marine disasters and enhance the early warning capacity, the overtopping risk of seawalls along Sanmen Bay was evaluated by using the coupled Advanced Circulation model (ADCIRC) and Simulating Waves Near shore model (SWAN). Calculation of multiple scenarios was conducted and the results show that the storm surge level caused by the typhoon is relatively high in the Sanmen Bay except Shipu watway, revealing a strong regional difference. When SLR is combined with storm surge and waves, the total water level can significantly increase the risk of overtopping. With the intensification of the typhoon, the length of overtopping seawall increases rapidly, while the power plant area remains safe. This research could provide scientific support for disaster prevention and mitigation of the seawall in Sanmen Bay.