The invention discloses a novel open-sea deep foundation pit support structure, which belongs to the technical field of a foundation pit support structure; and the novel open-sea deep foundation pit support structure mainly consists of a plurality of steel cylinders which are plugged into a hard soil layer and a plurality of water-stop cells, wherein the steel cylinders are distributed along the side boundary of a foundation pit, each water-stop cell is arranged between every two adjacent steel cylinders, and the steel cylinders are matched with the water-stop cells to form the foundation pit support water-stop structure. The novel open-sea deep foundation pit support structure is compact and reasonable in structure, high in working efficiency, large in construction and operation area and good in water-stop effect and used for supporting the foundation pit in open-sea operation.