Abstract: The capability of marine engineering maintenance and emergency repair is not only crucial for ocean exploration but also a powerful support for infrastructure such as nuclear and hydraulic power industry. Among all the techniques in this field, underwater laser repair has been one of the most popular research directions which holds great promise. Laser repair as a commonly used technology in ordinary environment has been successfully translated to numerous marine engineering applications researched by different industries such as nuclear power, hydraulic power, petroleum extraction and transportation, and ship maintenance. To further investigate the underwater laser repair technique, a comprehensive review has been done to understand current challenges and corresponding solutions. The process problems and their mechanisms of laser repair have been investigated in different methodologies such as underwater wet, hyperbaric dry and local dry method, then the improvement and research progress of main problem's mainstream solutions are compared, followed by the discussion and suggestion of the future research directions.