The invention relates to the technical field of ships, in particular to a cargo transport ship. The cargo transport ship comprises a ship bottom, ship sides fixedly connected to the ship bottom and apropelling device for providing driving force, wherein the ship bottom and the ship sides define a cabin. The cargo transport ship is characterized in that the ship bottom adopts a double-layer structure and comprises an inner ship bottom and an outer ship bottom arranged in parallel at an interval; a plurality of sealed cavities are formed in the inner ship bottom and the outer ship bottom. The cargo transport ship requires no ballast water and thus the building cost can be reduced.