The reinforcement and renovation of the existing wharfs can effectively improve the quality and safety level of the wharfs,and promote the intensive utilization of infrastructure.Taking a 35,000-ton bulk cargo terminal project that has been in service for many years in Hainan as an example,this paper studies the reinforcement practice of the main caisson structure damage,and puts forward the solution for underwater repair.The results show that: 1) the damage condition of caisson can be accurately judged by detailed underwater photography and exploration.2) For the phenomenon of caisson wall breakage and serious bare rust or fracture of steel bars,high pressure water flushing or gouging can be treated first,and then the formwork and high-strength grouting material are supported,and the underwater coating material is used to repair the caisson wall.3) For the phenomenon that the packing part in the caisson drops,the underwater non-dispersed concrete can be poured in the caisson compartment as a whole.The field test shows that the construction repair technology meets the design requirements,and the corresponding quality control points and underwater operation safety management requirements are summarized,aiming to provide reference for similar projects.