Abstract: Based on an analysis of the draft characteristic of SWATH, It is pointed out that SWATH will bring grounding strength question as the submerged body of deep draft easily collide with bed or ground on bed. These technologies such as the grounding strength and the capability of collision and anticollision design of SWATH are the key technologies distinguished from conventional ships. The configuration characteristic and the process of sailing and anchoring are fully analyzed. The possible grounding modes of SWATH are the whole grounding of the twin-submerged body, the single submerged body the muhipoint grounding of twin-submerged body and the singlepoint grounding of the single submerged body. Analyzing the mechanic behavior of every grounding mode, we can think the grounding process as contact phase and grounding phase. In the contact phase, SWATH usually is locally damaged :the submerged body is sunken or come into crevasse, or probably bringabout damage of the whole ship such as the fracture or apparent plastic distortion of the backup post and the cross structure. In the grounding phase, the hull will ascend at the grounding position, the extent of ascending will be enlarged with the decrease of the outboard water line. It will lead to damage of the whole ship or duration damage of local damaged structure . The study of the ability to keep integrality and inflexibility of the whole ship and the ability of resisting the duration damage of local damaged for SWATH structure are emphasized.