Preparation of manufacturing process as well as serving of manufacturing process must be organized in a common functional unit. Operational preparation of manufacturing process is particularly important segment of preparation because it defines the production schedule and provides data for all the necessary resources needed. Operational preparation activities are complex, and they can directly affect the production effectiveness. In case of the high-volume production of technologically complex product family in the multi-product, multi-stage manufacturing system with limited flexibility, it is common that the manufacturing system is highly utilized. Its high utilization narrows possibilities for finding most economical solution in process of operational preparation. The basic aim of the research is to develop an advanced computing model for computing the batch size and their input order as two main areas of research in order to minimize overall production costs and fulfil delivery requirements. The computer-assisted developed model will provide a realistic model and simulation of the production process. With application of the optimization method it will be possible to define the optimum batch size and their input order for each product. Research results will be applicable in production environments, especially those engaged in the production of a wide assortment of technologically complex products.