In order to ensure the safe and reliable operation of underwater base plate and provide safety guarantee for oil exploitation, aiming at the underwater working condition of tension leg platform which is suitable for 300 m water depth, the basic design methods including structural design, foundation design and anti-corrosion design are proposed, so as to realize the independent design of underwater base plate, form the independent intellectual property rights of underwater foundation plate, and reduce the development cost of oil and gas field. The research is of important economic value and safety significance for oil and gas field development.