The hierarchical structure of the Internet of Things (IoT) consists of multiple nodes that are divided into major nodes at the upper level of the network and general nodes at the lower level of the network. A hierarchical topology is very practical because it facilitates design and analysis tasks. Among other things, it enables cascading failure analysis, which is necessary to test its effectiveness. This paper presents an approach to analysis of cascading failure in the hierarchical structure of IoT caused by possible overloading of this network. Theoretical and simulation results allow to determine the reliability of such systems under conditions of their extensive use.