The monograph is devoted to the system analysis of approaches to the building of models of chemical-technological systems, on the basis of which a systematic concept of building of models and the issues of solving decision-making problems for managing the operating modes of technological objects is proposed. The problems of the development of mathematical models and the optimization of complex chemical-technological systems are investigated, using the example of technological objects of oil refining, in conditions of uncertainty caused by the lack of reliable quantitative information and the fuzziness of available information. The structure of the monograph consists of an introduction, the main part of four sections, a conclusion and a list of sources of information. In the main part of the work, the current state of the problems of mathematical modelling of technological objects of oil refining production is analyzed. Methods of mathematical modelling and decision-making in the management of technological objects according to environmental and economic criteria are chosen as the direction of research. Methods of building mathematical models of chemical-technological systems of oil refining in a fuzzy environment have been investigated and proposed, and models of the technological complex of the catalytic reforming unit have been developed. An approach to the creation of a package of models for system modelling of the technological complex of the catalytic reforming unit is described. An algorithm for the synthesis of models of a technological complex of oil refining based on fuzzy information is proposed. Expert assessments have been carried out to develop a mathematical description of the technological complex of the reforming unit, a method has been developed for carrying out expert procedures in a fuzzy environment. The formulations of decision-making problems for the control of the technological complex of the reforming unit are formulated and, based on the modification of various optimality principles, heuristic algorithms for their solution are developed. The properties of the developed algorithms for solving decision-making problems have been investigated and a method for their selection in solving specific production problems has been proposed. A mathematical formulation of the decision-making problem for optimizing the operating modes of the catalytic reforming unit in a fuzzy environment is obtained and the results of its solution based on the proposed fuzzy approach are presented. The structure is created and the main functional blocks of the computer decision support system based on the object models are described. The issues of software implementation of the developed models are considered and a description of the interface of the computer system for modelling the units of the reforming unit and decision support for optimizing their operation modes is given.