Statement of the problem. The aim of the article is to develop procedures for translating practical questions about the choice of optimal routes of the heat supply system into mathematical problems of multi-criteria optimization and the study of these problems taking into account a large number of different parameters of the system and their connections.Results and conclusions. A mathematical description is compiled of the route choosing problem for the heat supply system based on the methods of system analysis. As optimized criteria, the integrated parameters are discussed describing the main characteristics of the systems under consideration. Unification of the problem where some of the criteria must be minimized and the other one maximized is carried out by replacing the minimized criteria with inverse values. Using the example of the modeling problems the procedures are shown for finding optimal solutions. The visibility of such procedures is provided by the use of a quadratic (Euclidean) norm instead of the traditional summation of weight coefficients. The importance of correct scaling and choice of weight factors is shown in the study of the discussed multi-criteria optimization problem.