当前快速城镇化和外埠文化的强势植入，造成了城市街区外部空间形态“异常”趋同，文化断层成为了中国城市的普遍性问题。因此探寻现代化语境下的传统建筑、街区的外部空间形态地域性演替模式，为城市的有机演替提供科学的评价标准，有利于风景园林学科与建筑学科的科学推进。本研究以快速发展、外埠文化介入明显的民国重庆为例，对重庆民国历史建筑及群落进行实例分析考察，通过对空间句法的“凸性空间”再定义，分析构成其虚体空间的三大类型：区块、边界、节点，再结合实体建筑，明确建筑外部空间的领域范围、尺度和边界等；其次，通过外部空间的分节、动线、配置形式和空间意识等对建筑外部环境的“性格”进行分析，并通过聚类分析法客观总结重庆民国建筑的外部空间构成与特征；再以问卷调查分析法和SD法设定外部空间环境评价因子和标准，从而建构街区形态的地域适宜性导则，并为重庆城市特殊历史风貌的保护及其他历史城市地域形态特色建构提供科学参考。

Rapid urbanization and subsequent forceful introduction of foreign culture form “extremely” similar external space of city blocks, so the culture fracture becomes the common problem of Chinese cities. How to explore regional succession mode of external space of traditional buildings and blocks under the modern context, so as to provide scientific evaluation standard for organic succession of cities, is the surpass able scientific way of landscape architecture discipline and architectural discipline. Taking Chongqing with rapid development and obvious introduction of foreign culture in the period of the Republic of China as an example, this paper investigated and analyzed historical buildings and communities in the period of the Republic of China, defined “convex space” of space syntax, analyzed three types composing the virtual space: block, boundary and node, in combination with physical space buildings, and specified scope, dimension, boundary of external space of buildings. Secondly, from segmentation, generatrix, configuration form, space awareness, etc. of external space, this paper analyzed the “characteristics” of external environment of buildings and objectively summarized the composition and features of external space of Chongqing buildings in the republican period by using the clustering methodology. Thirdly, this paper set the evaluation factor and standard of external space environment by means of questionnaire analysis and SD method; so as to establish the guideline for regional suitability of blocks, guide spatial design of city blocks in Chongqing and provide scientific reference for establishing featured regional space of other historical cities.