Abstract The article provides concise details about a hydraulic phenomenon known as the undular jump, that occurs under different conditions within different hydraulic constructions and can negatively influence on their operation and conditions. Therefore, the methods of modelling undular jump characteristics using physical and mathematical model are presented. Based on physical model of undular jump, the experimental data were obtained. Moreover, three mathematical models were considered and analyzed. The article gives the comparison of experimental data and data obtained by mathematical models. The advantages and disadvantages of considered mathematical models were specified. The novelty of work was in developing and improving mathematical model with taking into account the energy losses that are allowed to obtain the characteristics of undular jump with high accuracy.