The paper explores an approach to ensuring the sustainability of cyber-physical systems (CPS) based on graph theory. The existing approaches of ensuring the security of CPS are considered. To formalize the problem it is proposed to model the behavior of CPS based on graph theory. Representation of CPS as a graph allows to take into account the structural characteristics of the system under study that change as a result of attacking influences, as well as to produce compensating actions aimed at maintaining the sustainability of functioning