For high-gravity dams, the discharge structure determines the energy dissipation characteristics of the discharge flow, which in turn affects the safe operation of the hydropower station. A hydraulic model test was adopted in order to investigate the effect of the shape parameters of the discharge structure on the hydraulic characteristics of the discharge flow. The test results show that the decrease of the plunge pool length reduces the diffusion space of the submerged impact jet and increases the turbulence in the impact zone, which results in a reduction in the minimum time-averaged pressure of the bottom slab in the plunge pool. In addition, it leads to an increment of the peak root mean square (RMS) of the fluctuation pressure on the bottom slab and increases its safety risks. The decrease in the length of the secondary stilling pool leads to an increment in the underflow velocity at the outflux of the stilling pool and increases the scouring risks of the downstream. Moreover, the reduction in the height of the auxiliary weir results in a decrease in the time-averaged pressure and an increment in the peak RMS of the fluctuating pressure and safety risks of the bottom slab. It also results in an increment in the water depth of the secondary stilling pool and a decrease in the underflow velocity at the bottom of the jump zone. Meanwhile, the turbulent intensity and the peak value of the RMS of the fluctuation pressure decrease but the underflow velocity at the pool outflux increases.