The Dunhuang culture is a dazzling pearl of world civilization, and the Mogao Grottoes are a typical representative of it. The well protection of the Mogao Grottoes and the well inheritance of Dunhuang culture are the responsibility of the Chinese for the progress of world civilization. The architectural history of the Dunhuang frescoes is an important basis for refining the history of ancient architecture, so this paper takes 77 images of city walls in Dunhuang frescoes as the object, and interprets the historical picture. Image rewriting and extraction techniques of CAD are used to perform mathematical analyses such as quantitative statistics and correlation of the four first-level elements of the city wall images in Dunhuang frescoes, which including the city “shape”, city “wall”, city “gate” and the environment outside the city, as well as 32 sub-elements, and interpret the information in it. The study shows:The study categorizes the evolution of the city wall in Dunhuang frescoes by the appearance and disappearance of important elements such as city shape, walls, and gates as historical nodes into four periods: inheritance, development, maturity, and evolution. The city wall in the Northern Wei Dynasty to the Northern Zhou Dynasty belongs to the period of inheritance, and the social upheaval during this period made the city walls focus on defense. The city wall from the Sui Dynasty to the Early Tang Dynasty as a period of development. After the unification of the Sui and Tang dynasties, political stability led to economic development and the construction of cities. The elements of city walls in this frescoes period are gradually enriched, and show that the ritual system began to be established. The city wall in the Grand Tang to Late Tang dynasties were the period of maturity, a period of economic prosperity and development, when the technology and types of city walls matured, and the ritual hierarchy was established. The city wall in the Five Dynasties belongs to the period of evolution, the defense function of the wall reappeared in the frescoes with the emergence of the late Tang Dynasty local ruling regimes. In addition, the low-level local city wall has also evolved and matured.The shape of the city gate is the dominant element in the transformation of the city wall paradigm and historical staging, in which the emergence of a large number of corner towers in the Grand Tang can divide the evolution of the city wall into two periods. In addition, the shape of the city and its external environment evolved slowly during this period. City wall in Dunhuang frescoes form evolutionary paradigm of dominated by the connotative impacts of the ritual and music system, supplemented by the gradual guiding impacts of social ideology, policy, and construction techniques. Through the correlation analysis of the number of gateways, the opening of the citadel and the form of the roof, which reflect the ritual system of the city wall, it is found that the city walls of Dunhuang frescoes are in line with the ancient ritual system, and the ritual system is the main factor in the transformation of the city wall paradigm.The images of city wall in Dunhuang frescoes are formed under the combined effect of multiple factors, which is dominated by the ritual system. According to the paradigm theory, the images of city wall are historical images close to the reality of the archetypes formed with the painters reached the state of expression of the “collective unconscious”. Therefore,although some of the city wall images differ from the realization, it can still consider the images of city wall in Dunhuang frescoes to have the paradigmatic characteristics of ancient Chinese cities, and regard them as the mapping of the real cities in ancient China.The study of Dunhuang frescoes architecture is of great significance in supplementing the historical materials of ancient architecture. According to the research, although some of the city wall images differ from the realization, but it can still build the ancient city wall image library by them through the exclusion, screening and organization based on historical data. This paper proves that the images of city wall in Dunhuang frescoes comprehensively display the rich and three-dimensional image of ancient city walls, and at the same time, it can also provide theoretical reference for the construction of the image library of ancient Chinese city walls and the archaeological research of ancient cities.Dunhuang frescoes shows the historical picture of ancient China’s architecture for thousands of years, which is an important historical material for the study of China’s ancient architectural research, especially the pre-Tang Dynasty architecture. In future research, it can be studied from the ancient planning ideas, the construction of human settlements, residential architecture and garden architecture and other directions in Dunhuang frescoes, and provide new historical materials for the history of Chinese architecture and urban construction. In addition, 3D restoration modeling of the images of city wall in Dunhuang frescoes can be carried out to enrich the historical materials of ancient Chinese architecture with more intuitive and real information.