Abstract: This paper analyzes the characteristics of urban traffic system when traffic congestion occurs at first. After indicating the importance of establishing intelligent decision support system for urban traffic congestion management, the design idea, system framework, function and method for realization of system are proposed. A knowledge-based decision system is realized, which contains abundant congestion management knowledge and solves the decision problems by combining the qualitative reasoning and quantitative calculating. At the same time, the practical system has been developed according to this paper. The effect of the system operation reveals the construction of the system is feasible.