Association ability refers to the ability of the subject to have association activities for the purpose of obtaining effective motive force of development, it forms the fundamental development force of both the subject and the human society. Association ability is the multiplication product of association quantity and association quality. Association quantity refers to the multiplication of association scope, speed and frequency while association quality is determined by a series of association structures, including the structure of association subject, the structure of association object, the structure of association content, the structure of association intermediary, the structure of association subject and object and the structure of association time and space.