Abstract: The research methods of hydraulics are diverse and each method has its characteristics. It is more concerned for the similarities and differences of reached achievements from all kinds of methods. Based on the bottom outlet of flood discharge with high water head in one hydropower station, the simulation and observation are carried through for the hydraulic issues by applying the physical modeling experiment, the prototype measurement of hydraulics and the time-averaged turbulence mathematical model. The adaptable scope and degree of three kinds of methods are identified. It is identical well for the simulated results of three methods with the macroscopic hydraulic flow state, bottom flow velocity, time-averaged pressure and aerated cavity. Meanwhile, there is a certain difference in the simulation of flow profile. The fluctuation prototypical water surface and longitudinal diffusion of water jets are larger. The achievement can be used to lead the selection of research method and correction of achievement for this type of hydraulic issues.