Korea has carried out many reclamation projects for agricultural land and water since 1980, because the south and west coasts of Korea were very suitable to reclaim. The original goal of Saemangeum seadike, the longest one in Korea, was the construction of the facility just for reclaiming land from the sea recently there has been diverse social changes like rise in the level of living, a five-day work and so on. Multi-functional and multi-land use sea dike is considered more than just simple-functional facility for agricultural reclaiming. This study tries to provide design plan of each open space as the environment-friendly development plan of Saemangeum seadike for multi functional facility with concept of 5E, Esthetic, Education, Ecology, Entertainment and Energy. And then this study suggest that Greenway, Inner slope of seadike, Observation platform location, Photo-station and program of ecotourism is focused on educational experiences in the whole area of the seadike.