Early Chinese city planners and builders succeeded in creating a imperial ideal city - Beijing. The spatial order of Beijing expresses the elaborate system of imperial hierarchy (meaning). Since the founding of People's Republic in 1949 as all the physical elements which defined the old spatial order have changed, the Chinese State attempted to reconstruct a new ideal city -a people's capital of socialist era. Some of these changes ignored the historical and aesthetic values of the traditional elements for utilitarian functions. This thesis examines the transformation process of this ideal city in terms of the physical elements and sociological perspectives, identifies the unique order and meaning of urban space in the ideal city - Beijing, and articulates some design principals that could be used to reconstruct a new ideal city - Beijing, express the new ideology of the people in the socialist era and preserve the historical and aesthetic values of traditional elements.