In this paper, a three-dimensional elastic-plastic model was established based on the finite element software. Relying on a tunnel slope project, the influence of "bolt + anti-slide pile" support parameters on the safety factor of slope stability and the maximum shear strain was discussed, and then the best support scheme was obtained. Through field monitoring and numerical simulation, the deformation characteristics of surrounding rock of slope and tunnel with or without this support scheme were compared. Using the distribution characteristics of anti-slide pile stress and bolt axial force, the support effect of this scheme is clarified again. The results show that the best support scheme was A (anti-slide pile 14 m, bolt 14 m), the safety factor of the slope after support is significantly improved, and the anti-slide pile has a greater impact on the safety factor of the slope than the anchor bolt. Compared with the condition without reinforcement, the horizontal displacement and vertical displacement of the slope under combined support are significantly reduced, and the range of soil deformation area is significantly reduced. The anti-slide pile mainly bears the compressive stress, and the maximum value appears in the middle of the pile, which generally presents the distribution mode of "large in the middle and small at the upper and lower ends". The axial force of bolt decreases linearly with the increase of anchorage depth. The measured data of tunnel deformation are basically consistent with the numerical simulation results, and the combined support scheme has a significant effect on controlling tunnel deformation.