Automated control of discrete manufacturing processes and their simulation must be based on a unified formalization, which makes it possible to describe a wide class of manufacturing systems, processes and conditions. This paper discusses an approach to creating a formalization method on the basis of artificial intelligence (AI) and the object-oriented approach. Modified production rules were chosen as such a formalism. The method of knowledge representation about manufacturing systems suggested by the authors makes it possible to create systems of control and simulation of manufacturing systems without using rigid decision-making algorithms. The use of the object-oriented approach increases the clarity and ease of manufacturing systems description for simulation. A structure of a developed production-rules-based simulator is also presented. A simple example gives an idea of the possibilities of the simulator.