The aim of this paper is to explore the transition in the architectural characteristics of the ancient Vietnamese housing in Mekong Delta, in Southern Vietnam from 1858 to 1945. For this purpose, this study selects six ancient houses to determine the architectural characteristics that reveal the relationship between society and architecture during this period. Then, these ancient houses’ characteristics are analyzed based on six factors which are settlement characteristics, planning scheme, facade, structure, material, and interior decoration to show the transition in their architectural style. Six factors of ancient houses are surveyed by three methods: using of the electronic distance meter to determine the size of houses, taking photos and drawing of the houses to analysis the architectural characteristics and interviewing the landlord to get information about ancient houses. As the results, the study explored the difference in the ancient houses style which is strongly affected both by French style to their facade and Chinese style to their interior decoration, but the spatial structure is still remained to Vietnamese people. In conclusion, the characteristics of selected houses should be considered in detail as a reference to the current design goals.