全球城市是经济全球化高级阶段的必然产物，经济全球化的基础是交通和通讯构建起来的网络；在交通和通讯网络基础上，贸易把世界范围内各层级城市链接起来，形成了不同层级的城市网络，一开始是区域的城市网络，接着是国家的城市网络，然后是全球的城市网络，最终形成了城市网络层级；高层级的城市网络是本层级与低层级的城市网络的累积和叠加，譬如，全球的城市网络就是全球的城市网络、国家的城市网络和区域的城市网络的累积和叠加，构成了"金字塔"城市网络结构。与城市网络的层级性相对应，在各层级的城市网络中，区域城市、国家城市和全球城市逐步培育和形成；在高层级的城市网络中，本层级与低层级的城市构成这一网络中的城市格局，譬如，在全球的城市格局中，区域城市、国家城市和全球城市构成了"金字塔"城市等级结构，全球城市处于这个"金字塔"的顶端。遵循上述全球的城市网络和全球城市的变迁轨迹，可以总结提炼出全球城市演进规律，全球城市的创建必须遵循这一规律。

As a result of development of globalization at the high end, global cities are usually built on the network of global transportation and telecommunication. The network started from a regional network between cities to a city network within a nation, and ended in the global city network. In such a development, international trade plays an important role for connecting cities at different levels. A city network at higher levels is the accumulation of the networks below it. For example, the global city network is a pyramid of the accumulation of the global city network in a narrow sense, national city networks and regional city networks. Accordingly, regional cities, national cities and global cities are cultivated at respective levels. For a city network of high ranks, the layout of the network consists of cities at its level and below. For this reason, the hierarchical global city network consists of regional city networks, national city networks and the global city network in a narrow sense. Meanwhile, global cities stand at the top of the pyramid. Based on the discussion above, we finally come to the law behind the changes of global cities, which we should follow in the construction of global cities.