Abstract: With the development of nuclear power, marine engineering and development of deep-sea resources, the importance of underwater welding technology has become more and more prominent. The research progress of underwater explosion welding, underwater friction stir welding, underwater wet welding, underwater dry welding, and underwater local dry welding technology in China and abroad were summarized. The advantages, disadvantages and applicable fields of different underwater welding methods were expounded. The preliminary application of underwater welding equipment research units and the development direction of future underwater welding technology were introduced, which can lay a foundation for the further application of underwater welding technology.