A model decision-making support system (a model of the UrFU-MMK blast furnace process) for diagnosing and predicting technological situations of blast furnaces is considered. The main model blocks allow calculating material and heat balances, simulating thermal slag and gas-dynamic operating modes of blast furnaces, choosing the composition of the blast furnace charge. The model system is implemented as a set of software modules and integrated into the information system of PJSC «Magnitogorsk Iron and Steel Works» (MMK). The module for calculating the material and heat balances of smelting makes it possible to calculate the balances of Fe, S, Mn, Ti. The introduction of the software module «Slag Mode» allows determining the most important properties of the slag melt for realizing the normal slag mode of smelting, finding the ratio of iron ore materials providing slag with proper viscosity and viscosity gradient properties, and producing good quality cast iron. Introduction of the program module «Gas Dynamics of Blast Melting» - calculate and visually display the gas-dynamic characteristics of the layer of charge materials, as well as evaluate the change in pressure drops and the degree of balancing of the charge in individual furnace zones in the design period when the parameters of the loaded charge and its properties change. The results of the practical use of the developed system are presented, recommendations on how to solve technological problems are given.