Abstract: The military defense environment has become a part of a city in the development process, representing the city's culture and history. The transformation and protection of the military defense environment, regardless of the form language or the cultural connotation it delivers, both come from the revelation gained from land formation and development process. From the perspective of urban development, this paper summarizes the development characteristics and influence factors of military defense environment since the Middle Ages. Through the typical case analysis of the transformation of the military environment such as the Dutch Waterline, Mountain Montjuic and the Presidio, the enlightenment in the protection and transformation of the military defense environment is summed up. After the transformation, the historical military defense environment needs to embody site spirits, remodel the connection between fields and urban spaces, and need to re-establish the interaction between people and places through the sustainable management mode.