The area and the boundary are the two basic factors of political division. The brand-new city-type political division which initiated in the Republican Period was originated from the former regional-type division. At the very beginning, where were no existing laws to regulate the setting up of cities. Therefore, the exact area of the city remained the primary problem to be solved between the newly established city and its original regional political division. The research on the process of administrative demarcation of Nanking City in particular revealed the variety of conflicts appeared during the demarcation of city-type political division and its impact on the completion of city system in Modern China.