Abstract: As more submarine pipelines are put into service and operated for extended periods, the issue of corrosion in aging submarine pipelines has become increasingly severe. However, maintenance costs for offshore oil and gas fields are typically constrained, despite their high production pressures, leading to an urgent need for low-cost and highly efficient in-situ repair technologies for these pipelines. To address this need, this paper presents a systematic review of the characteristics and challenges associated with traditional repair technologies for submarine pipelines. It particularly focuses on the features and applications of three new in-situ repair technologies: lined composite hoses, the insertion of reinforced thermoplastic pipes (RTP), and in-situ internal coatings. Research results are summarized as follows: ① The repair technology based on lined composite hoses can effectively prevent the progression of corrosion in repaired pipelines by isolating the conveying medium from the pipeline itself, thereby extending its service life. However, the construction process is challenging, and the technology is relatively complex. ② The insertion of RTPs as a repair technology allows the RTPs to replace the submarine pipeline for medium transmission while maintaining resistance to corrosion from both the medium and seawater. Nonetheless, the reduction in diameter of the RTPs complicates the insertion process and presents technological challenges. ③ The repair technology utilizing in-situ internal coatings is suitable for pipelines with remaining wall thickness and strength that still meet design and operational requirements, regardless of their intended use, including the transportation of water, gas, and oil. The concluding section further discusses the application scenarios and future research directions for these three new in-situ repair technologies, providing valuable insights for their continued research and application.