Abstract: The mechanism difference between intelligent control and traditional control lies in that the former has been utilizing directly related knowlege of human being.The intelligent control has two aspects of conditional factors,i.e.,the requirement of sufficient knowlege about control and the necessity of establishing a proper structure of knowlege application.This paper introduces a blackboard model in expert system into the mechanism analysis of intelligent control.This model,after improvement,becomes an intelligent control structure with better adaptability,which not only contains various intelligent control fashions how available,but also is suitable to several traditional control fashions.At last,we present an actual example of intelligent control system design in connection with practical problem.