Modern complex chemical-technological systems as automation objects are distinguished by the presence of a large number of controlled and uncontrolled parameters, high productivity, technological modes intensity and ongoing technological operations continuity. The proposed article focuses on the actual problems of analysis, modeling, development of a mathematical formulation and solving the control problem, which is important in the chemical industry, the technological process for producing propylene glycol, which is widely used in various industries, in particular, as a working fluid in hydraulic systems, raw materials in production antifreeze, varnish and paint, tobacco humidifier in the food industry, in the pharmaceutical and cosmetic industries, etc. Here, due to the complexity and impossibility of taking into account factors that are difficult to formalize, changes in technological parameters and process characteristics over a wide range, and the difficulty of monitoring the states of the process under consideration, the apparatus of fuzzy set theory is used. Mathematical models of the process under study are constructed on the basis of the estimating the maximum probability method, in the form of fuzzy regression dependencies connecting the perturbing, control and state parameters of the object under consideration. On the basis of the obtained fuzzy models, a physically based mathematical formulation of the problem of optimal control of the object under study is formulated and a self-adjusting automatic control system with a fuzzy controller is built, which ensures the optimal functioning of the object under conditions of incomplete information.