With the development of large coastal ports, the grade of the designs of marine structures is also enhanced and selection of appropriate type of marine structures according to local conditions is one of the key researches in building of terminal structures. This paper analyzes the marine structure selected for the 200 000 t ore terminal for the iron and steel base in Fangcheng Port, using the large-diameter circular caissons with no wave breaking holes，this method can provide a reference for other similar projects.