The high complexity of planning knowledge and the difficulty of structuralization have fostered the uneasy procurement of professional knowledge and have deterred the development of urban planning support systems. A new type of case-based system has received extensive attention recently. This article presents a new case-based planning support system approach and key techniques of system development to overcome the inadequate developments of previous urban planning support systems. In this article, we study the design ideas and methods of system operation for the phase of case-based development and procurement; on the other hand, we also study how to apply the knowledge engineering techniques which are based on cognitive theory to actually control user's behavior to further become the basis of system design. Meanwhile, we operate an experimental system to examine how the developmental theory and the methodology of the system are formed.