The paper deals with mathematical models used in the diagnostics of the technological system states: structurallogical model; causal model; state space model; interval parametric models. The problems of diagnostics states and control of technological safety of chemical production are discussed. It is shown that the core of modern management system of technological safety of chemical production, is a diagnostic system of chemical-technological process states and are some common features of the establishment and use of diagnostic systems for chemical-technological process. The conclusion about the need to build diagnostic systems based on chemical-technological process class of discrete models, which allow the analysis of the system availability under uncertainty information about diagnosed object.