Prototype measurements, physical modeling experiments, and numerical simulation are effective tools for studying hydraulic issues related to water conservancy and hydropower projects. To investigate the adaptability of these three methods to a new energy dissipation technology called the horizontal gyrating discharge tunnel, which is based on the Gongboxia horizontal gyrating discharge tunnel, the results obtained by applying the three methods were compared and the adaptability of the methods for different parameters was determined. The results indicate that the simulated results of the three methods are in agreement for the macroscopic flow pattern, pressure near the wall, and energy dissipation ratio. The annular cavity length of the physical models and numerical simulation are different from the results of prototype measurement, which further affects the accuracy of the hydraulic parameters in the vertical shaft section; therefore, it is necessary to correct it in engineering design. The numerical simulation and the model test are feasible methods to study gyrating cavity shape and velocity in the gyrating discharge tunnel and can effectively overcome the limitations of prototype measurement technology; further, the numerical simulation has many advantages. A 1:40 and above scale model is an effective method to study the ventilation characteristics of the ventilating shaft in a horizontal gyrating discharge tunnel. The results can be used for the selection of research methods and correction of results for this type of hydraulic issue.