Abstract: To solve the fatigue problem of the dense welds of the local hull structures, by simulating the actual service environment, the engineering fatigue tests and structural stress simulation calculation are carried out on two types of local dense weld structures, and the methods to improve the fatigue performance of the dense weld structures are proposed. It is concluded that under the seawater corrosion environment, as the distance between the adjacent welds decreases, the peak stress of the structure increases, and the fatigue life of the dense weld structures decreases. When the distance between the adjacent welds is small, the surfacing and repair welding methods can effectively improve their fatigue performances.