The hydraulic characteristics and cavitation erosion near the converse curvature section in the high-head and large discharge spillway tunnel have been important issues of concern to the hydropower project.In this paper,the evolutions of hydraulic elements such as pressure,flow velocity,wall shear stress,etc.in the converse curvature section are analyzed and the impacts of bottom aerator on hydraulic characteristics are discussed,with the commercial software FLUENT6.3 as a platform and combining the k-model and VOF method.The flow pattern in the converse curvature section of spillway tunnel is given by the three-dimensional numerical simulation.It indicates that the pressure changes rapidly with great pressure gradient from the beginning to the end of the curve.It also shows that the shear stress on side wall just downstream the end of the converse curvature curve is still increasing;the aeration cavity formed downstream the bottom aerator may cause the side wall pressure decreased to worsen the cavitation characteristics near the side wall.By means of the physical model experiment,the three-dimensional aerator composed of side wall baffling aerator and bottom aerator is studied,the baffling aerator suitable for the water flow conditions with water depth of 6.0 to 8.0 m and flow velocity of 35 to 50 m/s is proposed. The hydraulic characteristics and cavitation erosion near the converse curvature section in the high-head and large discharge spillway tunnel have been important issues of concern to the hydropower project. In this paper, the evolutions of hydraulic elements such as pressure, flow velocity, wall shear stress, etc.in the converse curvature section are analyzed and the impacts of bottom aerator on hydraulic characteristics are discussed, with the commercial software FLUENT 6.3 as a platform and combining the k-model and VOF method. flow pattern in the converse curvature section of spillway tunnel is given by the three-dimensional numerical simulation. It indicates that the pressure changes rapidly with great pressure gradient from the beginning to the end of the curve. It also shows that the shear stress on the side wall just downstream the end of the converse curvature curve is still increasing; the aeration cavity formed downstream the bottom aerator may cause the side wall pressure decreased to worsen the cavitation characteristics near the side wall. By the means of the physical model experiment, the three-dimensional aerator composed of side wall baffling aerator and bottom aerator is studied, the baffling aerator suitable for the water flow conditions with water depth of 6.0 to 8.0 m and flow velocity of 35 to 50 m / s is proposed.