In order to thoroughly research the hydrodynamic characteristics of a stilling basin with a drop sill, and provide a reference for its design and protection, the distribution characteristics, amplitude, and spectral features of the fluctuating pressure were studied based on physical model experiments. The experimental results show that the flow condition is the main factor influencing the fluctuating pressure, and the fluctuating pressure coefficient of the stilling basin slab increases and then decreases in the direction of streamflow, before finally stabilizing. The fluctuating pressure of the middle line of the slab is close to that of the side wall, and the maximum fluctuating pressure at these two locations reaches 5.1% of the total water head. The maximum fluctuating pressure occurs in the region near the chute sidewall extension line in the front of the stilling basin, and it reaches 11.5% of the total water head. Compared with a traditional stilling basin, the fluctuating pressure of the middle line in the front of the stilling basin significantly decreases, and the maximum difference reaches 55.2%.