At the time of globalization, people begin to scan and consider global problems, seek the global strategies to solve these problems and adopt corresponding global actions. People are taking the global system as the understanding object and the rebuilding object. When the global system occurs in human views, the proper understanding tool is needed to help us observe and consider it. The system theory is thus an understanding tool. The idea and method of the system theory can be utilized to research and explain the phenomenon of globalization, and as a result, to discover and find the essential and rule of globalization. This article will analyze the structure of global system, the attributes of global system, the governance of global system, the state of global system and the evolution of global system.