Анотація: The mathematical model «radiotechnical facilities – control system» is proposed and studied in this article, which determined connection between auditor and serving for control systems. The analysis of exciting methods of the development mathematical models for monitoring the technical state of complex systems is carried out, and their chief shortcoming is determined - the dependence on two independent models. Appliance of Petri net model to the development result of arithmetic model «radiotechnical facilities – control system» is the analysis of these findings. Model structure «radiotechnical facilities – control system» is suggested and represented as a graphical chart of Petri net. Arithmetic model is developed on the base of this graphic chart. Arithmetic model is checked against limitedness, reliability, storageability and coverability. The validity results of represented model are displayed in the article.