The invention relates to a converter station of a maritime flexible direct current transmission system. The converter station is characterized by comprising a combined steel structure building which is transversely divided into an upper end part and a lower end part, wherein the upper end part is longitudinally divided into three electrical rooms, the middle electrical room is a direct current field, and the two electrical rooms on the two sides of the direct current field are converter valve halls; the lower end part is longitudinally divided into five electrical rooms, the middle electrical room is a converter station water-cooling equipment room which is divided into front and rear two parts by use of a cable shaft, each of the electrical rooms close to the two sides of the converter station water-cooling equipment room is longitudinally divided into front and rear end parts, each front end part of the electrical room is a control protection chamber, each rear end part of the electrical room is a storage battery chamber, and the two electrical rooms on the outermost sides are connection regions; two connection transformers are arranged at an interval on the outer side of the combined steel structure building and next to any one connection region. The converter station of the maritime flexible direct current transmission system can be widely applied to the flexible direct current transmission systems of the offshore oil platforms.