Ethics was used as a building code in ancient China, not only to guide the construction of cities and buildings but also to define a strict hierarchy of architectural characteristics. The Fujian Tubao is a unique vernacular architecture and defensive rammed earth dwelling in China. The existing research on architectural spatial characteristics from the perspective of traditional ethical culture focuses on official architecture and residential-oriented vernacular architecture, and research on defensive dwellings has not yet been carried out. Based on data from our field research over the last ten years and 11 case studies, this paper constructs a research framework through five aspects, the spatial axis, functional arrangement, building volume, settlement pattern, and defense system, and analyzes the architectural spatial characteristics of Tubao under the ethical perspective. We find that although the Fujian Tubao is a rammed earth dwelling with mainly defensive functions, it also follows the traditional Chinese ethical concept of “clear-cut hierarchy and order of superiority and inferiority”; however, because of its special defense performance, it has added practical and defensive space to the traditional dwelling arrangement pattern. This study helps to provide a manual for the restoration and sustainable development of the vernacular architecture heritage of the southeastern coastal regions of China.