Natural gas hydrates are a kind of new energy resource that attract widely research interests. The open sea exploitation of hydrates consumes large amount of energy, it is not economic by directly using the exploited natural gas. Open sea floating wind farm is applied in this study to provide energy to the offshore platform for hydrogen production by reforming of methane. Floating wind farm is not studied widely and most works have been done to optimize the layout of turbines in different types and diameters, but less consideration is given to the layout design of wind farms in multi-period situation. Wind resource varies with seasons significantly and the location of wind turbines (WTs) can be changed in different time. This work proposes a new methodology to optimize the multi-period layout of wind farm based on Genetic Algorithm (GA) and Geosteiner algorithm. The objective is to obtain the largest annual economic benefit (AEB), including the annual production benefit (APB) and the cost of energy (COE). Finally, the optimal layout scheme is determined to help solving the layout problem of open sea wind farms. A 4.1 km × 4.1 km wind farm is applied in this study, it is indicated that under the condition of 12 periods layout, 1.7986 × 109 ¥/y of AEB can be achieved. Compared with single period optimization, AEB is increased by 6.3289 × 106 ¥/y by using multiple period optimization.