In this study, a parametric study was conducted to investigate the optimization of floating structure and blade pitch control settings for a semi-submersible floating offshore wind turbine. For the floating structure, a total of 11 different floating structures were assumed with varying column diameters or lower hull lengths. For the blade pitch control, we focused on the saturated control, called peak shaving, and six settings were assumed. The blade pitch control settings are a trade-off between the amount of power generated and the tower base load. Evaluation using the construction cost of the floating structure relative to lifetime revenue and the fatigue damage equivalent load on the tower base showed that the most efficient case was when the lower hull was slightly shortened, and the coefficient a that characterizes peak shaving was set around 0.9.