城市地下空间正由地上的“补充型空间”加速转型为支撑未来城市高质量发展的“第四空间资源”，在面临空间规划滞后、人本关怀不足、环境品质不高、技术集成度偏低等挑战的背景下，建筑学作为聚焦人居环境与空间营造的学科，成为推动城市地下空间绿色、健康、高效发展的重要支撑。本文从建筑学视角出发界定了城市地下空间的研究范畴，辨识了城市地下空间的战略地位与开发驱动因素，梳理了地下空间建筑学的国际研究进展和我国地下空间的发展历程；基于“立体规划 ‒ 空间营造 ‒ 技术集成与评价”三位一体的研究框架，阐述了集约化与统筹发展的空间策略、人本导向下的设计响应、数字支撑与科学评价体系建构等亟待研究突破的关键议题；探讨了建筑学介入城市地下空间研究的方法创新与应用路径，包括面向早期设计阶段的建筑师友好型仿真模拟工具、多维感知的建成环境评价方法、地下空间安全韧性与“平战转换”机制优化、城市地下空间智慧运维技术。构建面向复杂系统的建筑理论与设计体系、探索城市深层地下空间开发利用、强化人本体验与弹性设计、完善多维评价与规范体系、推动“模拟 ‒ 优化 ‒ 评价”一体化的性能导向建筑设计，全面支持我国未来城市地下空间高质量开发与可持续利用。

Urban underground space (UUS) is rapidly evolving from a "supplementary space" into a "fourth national territory" that supports the high-quality development of future cities. However, UUS faces key challenges, including lagging spatial planning, insufficient human-centered design, low environmental quality, and limited technological integration. In this context, architecture, as a discipline centered on human habitation and spatial design, plays a pivotal role in enhancing the quality, adaptability, and sustainability of underground environments. This study defines the research scope of UUS from an architectural perspective, identifies its strategic importance and development drivers, and reviews both international research progress and the developmental trajectory of underground architecture in China. It proposes a three-dimensional research framework centered on "multi-layer planning, spatial creation, and technology integration and evaluation", and highlights critical research topics that need breakthroughs, covering spatial strategies for intensive and coordinated development, human-centered design approaches, digital support tools, and scientific evaluation systems. Furthermore, the study explores methodological innovations and application pathways, such as architect-friendly simulation tools for early design stages, multidimensional perception-based built environment evaluation methods, optimization of UUS safety resilience and peacetime-wartime transition mechanisms, and intelligent operation and maintenance technologies for UUS. By establishing architectural theories and design systems for complex systems, advancing the use of deep UUS, exploring human-centered and resilient design, improving multidimensional evaluation systems and standards, and promoting performance-driving architectural design integrating simulation, optimization, and evaluation, this study can provide a comprehensive foundation for the high-quality and sustainable development of future UUS.