This paper holds the view that the theory of district comparative advantage, the theory of district structure optimization and the theory of district market operating form an united theory frame of the strategy theory on economic development of county district. The theory can be generalized as: the theory of district comparative advantage is the positioning theory of the county district economy; the theory of district construction optimization is the directional theory on the county economy, and the theory of district market operating is one which brings the above two theories into effect. The paper also analyzes the four types of market operation at county district.