Abstract: The Program and Control decision Problems(PCDPs)are relatively macro and comprehensive,and the degree of structure is poor.it is difficult to determine information requirements in developing the DSS.In this paper,we describe the decision cognitive process by resolution of decision tasks,and discuss the cognitive limitation in the completing decision tasks by the knowledge classification declaration,and then give an exposition of the basic decision support functions and the three-layer hierarchical construction for developing the Program and Control Deci- sion Support System(PCDSS).

Key words: Program and Control Decision, Cognitive limitation, DSS