This paper aims to clarify the character of foreign diplomatic missions during the Period of the Republic of China in Nanjing, by focusing on positional distribution and exterior spatial composition. 30 countries, 51 locations of foreign diplomatic missions have been confirmed from documents. Most of the foreign diplomatic missions are located in NO.1 Residential District which is planed by《Plan of the Capital》, under the influence of district planning and social class. The characteristic of exterior spatial composition can be divided into three groups. In Group A, the main building is surrounded by large exterior space, and entrances are emphasized by portico. Medium-scale exterior space, comfortable and gracious environment which created by entrance and green space, are main character in Group B. Group C makes good use of the combination of garden and traffic line to create a livable condition in limited space.