When there are the strong waves, green water phenomenon has a number of negative effects on ship or floating structures such as damaging structures on the deck and degrading the stability of the ship. Floating production storage and offloading vessels (FPSO) are commonly operated at a certain position and located to encounter mainly bow waves for the purpose of a decrease in roll motions.This study is focused on the analysis of the effects of the bow flare angle above the free surface on the hydrodynamic loads associated with the green water phenomenon.When designing the bow flare angle of the FPSO considering the influence of the green water, it is very important to understand the amount of the green water and the impact load on the superstructure on the deck. These are the functions of the bow flare angle of the FPSO as well as the freeboard exceedance level.Firstly, this study discusses the water level on the deck. Then the flow velocities on the deck are presented. And the pressure on the deck is also considered. Finally, a method of determining green water impacts on structures on the deck is presented. For these four sections, the relation with the wave height and wave period level are given.