Abstract: Due to fine sand’s unique physical properties and susceptibility to erosion, the protection of fine sand bank slopes is of paramount importance. Taking a portion of the Xiang River’s fine sandy bank as the research object, considering this area’s high rainfall frequency, fast flow velocity, and susceptibility to scouring of the riverbanks, the anchor rod-concrete prefabricated grid revetment structure is proposed in this study. The three-dimensional mathematical model of slope protection is established by using FLAC3D, a finite difference software, and incorporating the selected terrain and soil property parameters of the fine sandy slope section. The impact of this revetment structure on the stability of the slope is discussed. The results show that under the action of anchor rod tension and the self-weight of the prefabricated grid, the stress field exhibits a zonal distribution. The anchor rod-concrete prefabricated grid revetment structure greatly constrains the horizontal displacement of the soil mass, weakens the development of the slope’s plastic zone and the increment of maximum shear strain bands. The safety factor of slope stability is significantly improved. The length of the anchor rod and the angle of insertion into the soil have a significant impact on enhancing the overall stability of the fine sandy slope. An anchoring scheme with an 8-meter long anchor rod and an insertion angle of 30° can be considered for practical engineering reference.