This research tries to study the establishment and transformation of urban detail planning regulations during Japan colonial (1895-1945) and postwar Taiwan (1945-1976). In the view of urban planning, I will discuss the function and characters of Urban Detail Planning in both periods, and take these experiences to refer the urban design in future. I will focus on the study of regulation of urban detail planning, including three parts: the system of building line, urban land re-planning and detail planning.