The invention provides a triangular-section power draft-increase ballast-free semi-submersible conveying ship. The ship comprises a main ship body, a power draft-increase system and a control system. The main ship body comprises an upright rounded-triangular-cross-section parallel body, a flow inflow section and a flow removal section, the upright rounded-triangular-cross-section parallel body is designed in an optimized mode to adapt to underwater near-surface sailing, the flow inflow section and the flow removal section downward incline to a blunt bow and a conical stern respectively. The power draft-increase system is a multi-wing combined system, comprises board side fixed negative lift horizontal wings, a controllable main lift adjusting wing combined appendage and stern lift adjusting horizontal wings, and is used for adjusting vertical force of the ship body under various loading conditions to achieve the optimal semi-submersible draft. The control system comprises a variable wing type section forward-leaning upright column, an inward-leaning light invisible upper construction part, shallowly submerged piercing hydrofoils and a stern controllable vertical wing, and is used for controlling the course and stability of the ship body. The ship is novel in type and high in subsequent expansion performance, is a tool for navy land battle force hiding, quick delivery and emergency transport of special civil materials in a route, and has certain research and application value in military and civil fields.