In recent years,there are a lot of overseas projects in the sea area where there is a main direction swell with a period of 15～18 s and a wave length of 130～220 m.The comprehensive analysis including construction feasibility,project cost,structural safety and so on is made against those wave with long period and strong wave energy.Meanwhile,based on the design experience of several other projects with the same kind of wave conditions and as per physical model tests,the design main points of mound breakwater under the action of long-period swell are summarized. Keywords:long-period wave;swell;mound breakwater;physical model test In recent years,there are a lot of overseas projects in the sea area where there is a main direction swell with a period of 15～18 s and a wave length of 130～220 m.The comprehensive analysis including construction feasibility,project cost,structural safety and so on is made against those wave with long period and strong wave energy.Meanwhile,based on the design experience of several other projects with the same kind of wave conditions and as per physical model tests,the design main points of mound breakwater under the action of long-period swell are summarized. Keywords:long-period wave;swell;mound breakwater;physical model test In recent years,there are a lot of overseas projects in the sea area where there is a main direction swell with a period of 15～18 s and a wave length of 130～220 m.The comprehensive analysis including construction feasibility,project cost,structural safety and so on is made against those wave with long period and strong wave energy.Meanwhile,based on the design experience of several other projects with the same kind of wave conditions and as per physical model tests,the design main points of mound breakwater under the action of long-period swell are summarized.