Modern technology has increasingly created man-made dynamic systems that cannot be easily described by ordinary or partial differential equations. Examples of such systems are manufacturing systems and computer/communication networks. The activity in these systems is governed by operational rules designed by humans. Therefore, the dynamics of these systems are characterized by asynchronous occurrences of discrete events. Such man-made systems are called Discrete Event Dynamic Systems. The study of discrete event systems and modeling, analysis, control and optimization of their behavior, are of great importance in control engineering. Petri Net has a special position among various methods for analysis of these systems, because of its graphical and mathematical characteristics and its many capabilities. One of the most important problems in manufacturing systems is production scheduling, which is considered as a discrete event system. A manufacturing system should produce the demanded products with high quality, with low cost and in a short time. In this work, solving production scheduling of steel-making shop of Mobarakeh Steel Plant is considered as a discrete event system. After modeling the system using timed Colored Petri Net., optimization of the behavior of mentioned system is considered using interactive man machine optimization technique which leads to improvement in efficiency and decrease of loss. In fact, for a list of products to be produced in a certain time interval, a time schedule is derived which is optimum with respect to certain performance criteria by satisfying some constraints of system.