In recent years, as a result of global competition, the efficiency and effectiveness of business processes are becoming much more critical than ever. Information technology constitutes a critical role as a strategic competitive tool in the global business market. In the previous paradigm, the holistic view was missing and ultimately did not contain real life constraints. The new paradigm is based on the systems approach and represents the real life circumstances of production with applicable and sufficient models. This study is based on an expert system for the scheduling of a manufacturing system. The expert system works with a unique algorithm, which has been developed in this paper. The aim is to develop an expert scheduling system which is realistic and applicable to real life situations. Job specification, machine competence, due date, earliest completion and minimum set up time are the factors which have been taken into account to achieve this aim. As a result, the algorithm achieves both applicability and optimality in solution.