This textbook discusses methods for solving practical problems based on graph theory and network models, studied in the framework of the disciplines "Study of Operations," "Mathematical Decision Methods," etc. In addition to the theoretical foundations, the textbook presents practical examples of the application of graph theory and network models: choosing a route in a transport network (traveling salesman task), placing electrical substations and new industries, loading equipment, optimizing the network schedule of a set of works by time and performers, estimating the maximum flow in the network, placing employees, using a decision tree, making decisions in a group.