In the study of folklore, one of the important tasks is the classification and systematization of the types of Russian fairy tales. To solve this problem, a mathematical model was created, which is a labeled graph. It is designed to identify the central events that define the plot structure of fairy tales. The present study was conducted using algorithms for aggregating graph-theoretical models of fairy-tale plots in order to simplify and generalize their structure, as well as subsequent interpretation. As part of the testing of the proposed methodology, 41 fairy tales (including recurring plots) and their corresponding graph-theoretical models were analyzed. The texts were taken from “Russian Fairy Tales” book compiled by A. Afanasyev. When forming the sample, the prevalence of the text in folk tradition and its typicality for Russian folklore were taken into account. A graph was assigned to each text, where the vertices denote characters, objects, and events, and the edges reflect their relationships (gifting, exchange, and event repetition). Using the example of the text “The Bold Knight, the Apples of Youth, and the Water of Life”, the plot of which includes many characters and their interactions, shows the aggregation procedure, which is the combining of similar elements of the graph in order to reduce its complexity without loss of information. This does not take into account the ordering of vertices and edges, and there is no predefined structure of a simple graph. The method was implemented in the “Folklore” information system. The best quality indicators are achieved with the number of vertices equal to ten and the significance threshold of communication indicators equal to 0.2.