This dissertation compiles evidence and offers analysis for all known buildings along the Yangtze River in China that were built during the Yuan dynasty, a short-lived dynasty ruled by Mongols from 1271 to 1368, and often considered a transitional period in Chinese architectural history. Investigated areas include Sichuan, Chongqing, Hubei, Anhui, Jiangsu, and Zhejiang provinces and Shanghai, which are grouped in to three major areas: Sichuan, the Middle Yangtze River and Jiangnan. Through this research, the author attempts to find out how individual Yuan buildings in south China differ and resemble one another, how they are distinct from contemporary buildings in the north, and how they can help us understand the transformation of architecture from Song to Ming. In order to elaborate the construction history, religious functions, and structure of each building, I surveyed textual as well as physical evidence by studying gazetteers and inscriptions, and measuring, drawing and photographing every building. This documentation of individual buildings is also combined with comparative studies involving Yuan buildings in the northern provinces of China. Through my investigations, I demonstrate that Yuan architecture in Sichuan can be described as a branch developed on the basis of Jin (1115-1234) architecture in the north. Yuan architecture in Jiangnan, on the other hand, follows the archaistic regional style ever since the Northern Song (960-1127) and also reflects the reinforcement of the twelfth-century architectural manual, Yingzao fashi. The regional disparity in Jiangnan and Sichuan is due to the transformation of the political situation that are caused by migration waves and the imbalanced development of economy ever since the fall of the Northern Song. The Yuan dynasty is undoubtedly a transitional period in two significant ways: old tradition generated under different pre-Yuan regimes, such as Song and Jin, developed separately under the rule of Mongols in different regions; and those regional styles of Yuan that were later absorbed by the new Ming official style that tried to revive of Song tradition as well as to establish a new powerful dynastic style to legitimate its rule.