The utility model discloses a novel warship broadside cup-shaped tube joint containing a steel copper composite plate. A tube joint body is comprised. The tube joint body comprises an outer ring which can be connected with a warship broadside steel plate and a copper inner ring. The outer ring is sheathed on the outer round surface of the copper inner ring. One end of the copper inner ring is a flange end which is connected with a warship broadside inner copper alloy sea valve. The other end of the copper inner ring is an outer side end which extends out of the warship broadside. The outer ring is composed of a steel ring which can be welded with the warship broadside steel plate and two copper rings. Two copper rings are respectively tightly attached to two sides of the steel ring. The lower ends of the outer sides of two copper rings are welded with the copper inner ring. The copper and steel composite cup-shaped tube joint is used, and the part which contacts the seawater is made of copper alloy which is the same as the material of the sea valve, thus potential difference corrosion of a flange is eliminated. Compared with a cast steel tube joint, the performances of inner wall corrosion prevention and sea creature prevention of the tube joint are greatly improved. The overall service life is no less than 10 years, and the warship repair cost is greatly saved.