The wave attenuation performance of multi-body floating breakwater is an important factor to determine its application value.Based on the three-dimensional diffraction theory,using the software of Ansys Workbench and AQWA Graphical Supervisor (AGS),the effectiveness of wave attenuation of the rectangular multi-body floating breakwater with different wave heading angle and draught of pontoon is studied.It is found that multi-body floating breakwater can reach the lowest transmission coefficient at 90 degree heading angle.Increasing the draught can decrease the transmission coefficient of multi-body floating breakwater,but declines the stability of structures.Therefore,we try to ensure that the floating breakwater head sea surface is perpendicular to wave direction,so that it can get a better wave effect.At the same time,we try to avoid to choose the large draught floating breakwater.