In order to ensure the launching safety of a ship with a thin and sharp form, a gravity longitudinal launching technology with full steel beam supporting hull is determined in view of its launching state and structural characteristics. The launching support reaction is determined, the local hull strength under the action of maximum support reaction is checked with the finite element method, and the launching arrangement of steel beam, steel beam fixing equipments, sliding way, and steel balls is defined. The feasibility and safety of the technology are verified by actual ship, which can provide reference experience for the launching methods and technological planning of similar ship forms.