As a sitting room in a city, square is a place of human life and production bearing political, economic, cultural, and religious functions. As the spatial carrier of public life, square is a place for citizens to converse, consult, criticize, and discuss concerning public interests. With the characteristics of the “public sphere”, it is the spatial expression form of public sphere. Through square space, citizens express their political claims and struggle for political rights, thus influencing political identification and political process profoundly. Square is related to political power closely. Space is an expression of power, so different forms of power create different spaces and political power shapes square. Political system is the external manifestation of political power. The development of the spatial forms, structures, and functions of square reflects the change of the political system.