Taking the slope of a tunnel entrance as an example, the slope instability mechanism was summarized and analyzed through engineering geological survey, and then the prevention and control design method was proposed, and the treatment effect of the slope was discussed in combination with the monitoring results. It shows that under the unfavorable conditions of the combination of the large pile side of the soft rock bedding slope and the outer structural surface of the slope toe, and the bedding bias of the small pile side, the slope toe forms a free face. At the same time, due to the structural deterioration, the interlayer bonding of the rock mass is poor, and the mud layer is locally developed. Under the influence of groundwater infiltration, the deformation and failure of the slope and the hole occur. Back pressure backfilling at the toe of the slope is a fast and effective means to prevent further deformation of such slopes. After the slope is treated with anti-slide piles, the slope stability is good. In addition to the pre-construction investigation, the construction stage investigation should also be carried out to investigate the development characteristics and combination of the external inclined structural plane of the slope. When there is a combination of the layer and other structural planes, the slope is free or the bedding is biased, and the anti-slide pile is an effective pre-reinforcement method.