In the large network system, the metropolis and central cities are having impacts, and thousands of small cities are presenting features affected by the mutual connection. Just like the scholar of urbanologist Jeb Brugmann pointed out, local affairs is no longer local. Constant urban constructions, especially the construction in the last half-century already formed an inter-connected global city system. The development of some cities is affecting the global city system. Even a little local case may be magnified to a global event and accumulate the globalization. It's uncontrollable for any countries, companies, or international organizations. The most important thing is, the globalization is based on the increasing cities and the cities are different from design, value and programs. These cities are interacting in many kinds of unknown ways in the new global city system.

Second, the ability and intension of cities to participate in global management is increasing. In the economic field, cities are becoming a great part in the economy of countries. With the economic globalization and informationization of society, the influences of cities have cross the border. The Italian scholar of futurology Ricardo Petra estimated "the power will fall in the hands of businessmen who are active within the scope of the world and of the alliance between the cities governments. Such city government will firstly promote its competition ability of global company."

At the same time, in the field of public diplomacy, the right of decision-making of the world trends to decentralization, a large number of decision-making and public fiscal expenditures moves from the central government to the city government. The decision-making scope of local government is quite wide, a large part of public expenditure and the right of decision-making are in the hand of city government; the local government of the city owns more policy levers and economic levers. Local government has greater power of decision in the aspects of local tax, land policy and so on; the trade dominated by local government rise sharply, the right of foreign trade transferred from the central to the local government and private company; the direction of the development in future urban has been largely in the hand of the local government, the central intervention is greatly reduced.

The former Under Secretary General of the United Nations Mark Malloch Brown said "Globalization probably will become the most local affair in the 21st century". The global management only can be achieved after all levels of government adopt it. The political willing and actions will dominate the economic and political agenda of the coming decades.

Third, the city diplomacy is a new kind of diplomacy contains huge innovation opportunity. Since the 21st century, the contemporary diplomacy is undergoing a profound transformation. Economic globalization, progress of science and communication technology, development of transportation, changes of population, immigration, energy and environment. All these changes are influencing the traditional diplomacy. All countries have realized the new trends; they are adjusting and innovating the diplomacy system to adapt to the changing international environment. President Xi Jinping in the recent speech said, we need to promote the people-to-people diplomacy, city diplomacy and public diplomacy. It's the affirmation of our countries' city diplomacy and also put forward a higher standard requirement to the future city diplomacy.

From the practical aspect, there are two features of China's city diplomacy: firstly, "the government together with the private". Compared with the people-to-people diplomacy, city diplomacy is more official; compared with official diplomacy, city diplomacy has the feature of non-official. Secondly, the dialectical unity of the central and local. City diplomacy is an important part of the total diplomacy and plays a special role of it. The city diplomacy aims at protecting the local interests and national interests. Its nature is to achieve the balance of national interests and the local interests.