Decision Support System (DSS) are commonly used in the manufacturing industry to assist management in decision making processes. There are several major types of DSS systems and each is useful for solving specific manufacturing problems. The development of intelligent DSS systems that can carry out high level reasoning is itself a challenge and a requirement by modern management. This paper illustrates the formulation of a DSS system (called Performance Decision System) that can be used for solving complex manufacturing problems. The DSS system is based on two major types of DSS; System Dynamics and Experts Systems.