Abstract: As a part of Shanghai international shipping center, Yangshan Deepwater Port fourth dock is located in the northwest of the first to third docks. It is formed by sea embankment around Particle Island, Zhushan Island, Turtle Island and Fish Reef. It is the world's largest dock built relying on the island. The dock is the largest and most advanced intellectualized in the world. The new technology is adopted on the basis of the foundation. It requires high exploration results and difficult technology. Many problems faced by the offshore area are not standardized. Investigation works include completely independent intellectual property rights and comprehensive set of key technology exploration platform series, novel sampling, soft soil test new technology, and sea mud as a whole. They reveal the port consolidation of dredger fill load deformation, and put forward appropriate and effective foundation treatment scheme. Optimization design for cost reduction provides a strong data support, and achieves good social and economic benefits. These innovations symbolize the breakthroughs in China's geotechnical investigation in China's offshore geotechnical engineering, and provide useful references for similar super engineering surveys in the future.