This paper presents the general form of control theory problem. Regarding on all primary research fields of control theory, such as optimal control, robust control, sliding model control, (artificial) intelligent control (which includes faults-tolerant control, self-adaptive control, fuzzy control, neural control and so on) and control for large-scale system, the paper summarizes the concepts, principles and ways of construction, and analyzes their priorities and drawbacks, as well as their developing trends. Finally, the paper prospects the future control theory and its characters.