The present application provides a semi-submersible immersed tube transportation and installation integrated ship and a construction process; the integrated ship includes: a deck structure; two floating structures, ballast water being able to be injected therein; and upper portions or top surfaces of the two floating structures are connected by the deck structure; and two support mechanisms, disposed on opposite sides of the two floating structures respectively; and each support mechanism is disposed at a lower portion or a bottom of the floating structure. The integrated ship can reduce the draught of the integrated ship carrying an immersed tube and realize the transportation requirements of shallow waterway.