Abstract: The Princes’ mansions of Qing Dynasty, which embodies the historical and cultural characteristics of Beijing， are mostly located in inner city of Beijing. Prefecture Prince Duans mansion has been destroyed and vanished in the development of Beijing city. Through literature consulting, comparison of historical maps and spot investigation, this paper analyzes the characteristics of the architecture and garden form, traces and arranges the historical evolution, building layout, form comparison, actuality of its garden and location of Prefecture Prince Duan’s mansion. This research has great significance for protection and utilization of the Princes’ mansions in Beijing.