In the proposed article, to study and control incompletely defined petrochemical technological systems, an approach based on fuzzy set theory is used. This approach is based on the incompatibility principle, which most accurately characterizes the current state of the managing complex systems problem, namely: the more complex the system, the more difficult it is to obtain its exact model. The incompatibility of the system’s complexity with the accuracy of its description led to the reasonable idea about the possibility of adopting a coarsened (fuzzy) model for the system, which would qualitatively fully correspond to it. A generalized universal algorithm for controlling complex, multi-connected, and multi-component technological systems described by a fuzzy model is proposed. This kind of fuzzy model is based on two main aspects: first, the qualitative aspect of the technological process; and second, the experience of technological personnel, based on the feedback principle. When constructing an automated control system, the constructed fuzzy model is represented as a multidimensional controller with many inputs and outputs.