Abstarct: Floating breakwaters are used to develop a safe environment that protects shoreline structures against impact of the waves. Using these breakwaters in places that the sea has an unstable bed for bearing the force of the materials and also in places with relatively deep depth, is substantially economical. There has been done some vast projects on our country’s shorelines and on the other hand because of the importance of designing shore protection structures that are practical and economically justified, floating breakwaters can be mentioned as one of the most important protection structures in these shores. Therefore the necessity of acquiring technical knowledge of the designing and the constructing of floating breakwaters, and also lack of practical experience in our country, shows the importance of investigating the aspects of this matter. Studies done so far on floating breakwaters, have most of the time focused on hydraulic properties of these structures like the coefficient of wave transmittance and the coefficient of wave reflection. So there’s a serious need to investigate the structural behavior of these breakwaters and assessing their compatibility with the environment. In this study operation of π shaped floating breakwaters and the effect of adding damper screens on reducing movement responses are investigated. To achieve this purpose operation of these breakwaters for different breakwater widths, draft, height of the vertical face, and width of the horizontal screens have been studied and assuming a varying geometrical body shape for the structure and setting the criteria as to the best seakeeping performance, models of the abovementioned structure have been optimized for environmental conditions of the Caspian sea. To develop the numerical model for the mentioned breakwater the software MOSES_7.05.042 has been used. To improve the practical aspect of the study, the simulation parameters and conditions have been chosen to suit governing conditions of the Caspian sea shorelines in Anzali port area. The results show that the draft is an important parameter for the matter of the floating breakwater efficiency. Also increasing the width of the structure is really effective for reducing the floating breakwater’s response. Furthermore, adding horizontal damper screens at the end of the vertical faces reduces rolling movements.