Institutional plot refers to the built environment with relatively strong political and power attributes in Conzenian School. Under the background of urban development and political change, the spatial organization and social relations of institutional plot changes with the use and accessibility, which has specific performance in core element, crowd flow, element organization and structure, reflect a lot of the political control of the city. It can be expressed in the following three forms: (1) Breakthrough of function, (2) Breakthrough of town plan and (3) Breakthrough of the accessibility. In this paper, two case studies corresponding to the above breakthrough processes were carried out in Beijing, which were located in the central location of traditional cities, the most representative expression of political space in China, experienced the historical change with political meanings from feudal to modern society. We believe that the findings can reflect the relationship between morphological transformation and urban political and social reform. In the process of socialist China’s transformation, the institutional plot and monumental space under the original feudal system have been transformed accordingly, which are long with the reshaping of society and citizens. A mechanism of influence should be established between the renewal of the institutional plot and the political, social and cultural conditions.