To meet the strategic demands of deep-sea exploration and security assurance, large-scale unmanned underwater vehicles (UUVs) featuring long endurance, extended range, high speed, and low noise have become a central focus in global marine technology competition. The advancement of these technologies directly reflects a nation's maritime capabilities, making it imperative to address the challenges of multidisciplinary design optimization (MDO) in achieving comprehensive high performance. This paper aims to systematically map the technical genealogy of large-scale UUVs, analyze key MDO bottlenecks, propose scientific evaluation criteria, explore practical solution pathways, and clarify future development trends, thereby providing structured support for technological innovation and engineering practice in this domain. The research adopts a combination of systematic review and comparative analysis methods. First, the technical spectrum of large-scale UUVs is examined, covering five primary propulsion modes (propeller, bionic, gliding, crawling, and hybrid) and their respective technical characteristics. Next, the study analyzes the coupling relationships and constraints among disciplines such as energy and power systems, acoustic stealth, hydrodynamic structure, and intelligent control. To overcome the limitations of traditional single-index evaluation approaches, a "multi-dimensional measurement system for overall performance" is constructed, integrating normalized indicators such as equivalent endurance, equivalent payload, vacancy ratio, and equivalent cost. Additionally, the paper summarizes the core parameters and technical characteristics of internationally mainstream models, and analyzes solution pathways for key challenges based on the current status of domestic and foreign research. The study reveals that the performance indicators of related disciplines are highly interdependent and mutually constraining, rendering traditional sequential design methods insufficient for achieving global optimization. The proposed multi-dimensional measurement system effectively shifts design goals from merely meeting individual performance indicators to pursuing optimal combinations of multi-dimensional performance, providing a scientific basis for evaluation. Comparative analysis of leading foreign UUVs (e.g., U.S. "Orca", Russian "Poseidon") highlights significant differences in equivalent performance indicators, reflecting their respective national strategic objectives and design philosophies. Key challenges are identified, including limited observation and communication environments, energy bottlenecks, and inadequate long-endurance reliability. Feasible solutions are explored through the application of intelligent technologies, advanced energy systems, novel materials, and digital twin frameworks. The research concludes that multidisciplinary design optimization is critical to surpassing the performance limits of large-scale UUVs. Future development is expected to follow four core trends: comprehensive evolution of intelligence, diversified breakthroughs in high-density energy systems, systematic integration of cross-domain collaboration, and deeper incorporation of bio-inspired design principles. Cutting-edge technologies such as artificial intelligence, advanced materials, and digital twins are anticipated to serve as key drivers for leapfrog development. This paper provides a systematic framework for balancing technical pathways and evaluating design schemes, offering valuable references for promoting the high-quality development of large-scale UUVs and supporting humanity's ability to explore, utilize, and protect the ocean.