Abstract: In this paper, the meaning of public space and the problem of public reconstruction are discussed through an experiment study of community formation and courtyard space adjustment in the old neighborhood of Dashilar in Beijing (2014-2017). Unlike the western theoretical circles, which generally regard public space as public life with political or social significance, the courtyard of Dashilar is a public space shared by several families but with little social life, and the neighbors are acquainted but remain strangers and the relationship can be tense and often in open conflicts.The paper begins with the perspective of "the property rights of public space cognition, management and usage" to sort out the historical process of Dashilar courtyards from state-owned urban space in the 1980s to privatized properties in the later years. In this process, even though residents understood that public spaces like courtyards and hutongs wereowned by the state, they still gradually encroached and divided these administratively neglected public spaces for private use. The act of encroaching on public spaces by residents is not only the result of housing shortage, but also influenced by the historical relationship between the state and the individual. Under such circumstances, the public space is no longer a mere functional material space, but is full of interaction between various actors, revealed both in the expansion of private space by individuals in daily life and in the "public disturbance" events by collectives in the construction of space. The experiment in this paper introduces two strong social interventions of "rebuilding social life" and "defining the public and private boundaries" to facilitate courtyard space adaptation. The two experiments ended in failure for the former and success for the latter respectively. This tells us that public reconstruction is not just about rebuilding social interaction between people, but also about adjusting the state-individual relationship and establishing the rules of living together in public space.

Key words: public space, property rights, social intervention, state-individual relationship