Abstract: Towing autonomous underwater vehicles (AUVs) have emerged as a transformative paradigm in ocean exploration, offering distinct advantages over conventional AUVs by deploying external payloads such as hydrophone arrays, magnetometers, and seismic sensors. By relocating sensitive measurement equipment away from onboard noise and electromagnetic interference, towing AUVs significantly enhance data accuracy while enable modular payload customization. This paper provides a comprehensive review of the development status of towing AUVs at home and abroad, offers an in-depth analysis of their key technologies, and highlights future development trends, providing a significant reference for the research and application of towing AUVs. The development of towing AUVs worldwide has been driven by both civilian and military demands. Countries like the United States, Japan, Italy, Russia, Singapore, and China have actively promoted the application of towing AUVs. Since 2005, various institutions and research teams abroad have conducted numerous experiments and applications. For example, the combination of REMUS 100 AUV and a hydrophone line array verified the feasibility of using AUVs as towing platforms. Singapore used a digital thin-line towed array sonar on an AUV to invert seabed sediment characteristics. Italy conducted GLINT tests to verify the anti-submarine capabilities of towing AUVs. In China, although the research started late, many domestic institutions have achieved certain results. The Shenyang Institute of Automation proposed a new observation platform, and the Chinese Academy of Sciences and Zhejiang University improved the underwater performance of line arrays. Regarding key technologies, the overall design of towing AUVs is complex and involves multiple aspects, such as the design and layout of various components. Different system structures and load-mounting positions must be considered, and multi-disciplinary design optimization can improve design efficiency and quality. The coupling dynamics analysis of the towing system is challenging due to its strong coupling and high nonlinearity. Modeling flexible bodies is key to accurate analysis, and combining multi-body dynamics, FEM (finite element method), and CFD (computational fluid dynamics) methods is a future trend. In terms of autonomous control, the stability of towing AUVs is affected by the marine environment. Motion control needs to deal with external load interference to improve robustness, and attitude control of the towed body is crucial for detection capabilities, achievable through winch or adaptive AUV maneuvers. Furthermore, intelligent decision-making systems that incorporate real-time towed body data are essential for enhancing operational adaptability in dynamic scenarios, such as obstacle avoidance or mission replanning. The future development of towing AUVs shows three trends. First, towing AUVs will become more specialized, aiming for larger load-carrying capacity, deeper operating range, higher operational accuracy, stronger robustness, and more intelligent decision-making. Second, towed loads will be more dedicated, with an emphasis on lightweight design, low-energy consumption, and intelligent integration. Third, towing AUVs may form clusters or heterogeneous networks to improve operational efficiency and accuracy, and they will exhibit stronger autonomy within the future network. In conclusion, this paper provides a comprehensive understanding of towing AUVs, covering their development status, key technologies and future trends. It serves as a guide for the design and improvement of towing AUVs, promotes the development of relevant technologies, and helps explore more application scenarios in the ocean. By addressing technical bottlenecks and embracing emerging trends, researchers and engineers can unlock the full potential of towing AUVs, driving innovation in deep-sea observation and marine resource utilization.