To ensure the safety of the protective structures of a stilling basin under high speed flow, stilling basin with a steel membrane is proposed as a new type of protective structure in which is a layer of thin homogeneous perforated steel plate is laid on the stilling basin slab. Based on hydraulic model test, the effect of the uniform perforated steel membrane on the distribution of the fluctuating pressure acting on the upper surface of the slab was studied. The results show that, when the uniform perforated steel membrane is laid, the fluctuating pressure intensity coefficient of the upper surface is reduced and the probability density function basically follows the normal distribution with more concentrated range of fluctuating pressure amplitude in the water rolling zone at the front of the stilling basin. The correlation and the spatial integral scale of the longitudinal points decrease, indicating that the vortex retention is reduced. The dominant frequency of the fluctuating pressure is basically the same, but the pressure fluctuation energy has a narrower band. Compared with the pervious slab, the protective structure of steel membrane can effectively reduce the fluctuating load acting on the upper surface of the slab in the front of the stilling basin, indicating that this new type of protective structure shows certain feasibility.