In order to change the status quo that traditional red sandstone cannot be used as highway subgrade filling due to its low strength, and to expand the application range of this kind of rock and soil, this study combines red sandstone with geogrid and gabion to form reinforced soil, and explores the reinforcement of red sandstone Mechanical properties under conditions. In the experiment, the coarse-grained soil triaxial shear tester was used to carry out the undrained shear test under the condition of 0-layer, 2-layer and 3-layer horizontal reinforcement, and the strength ratio parameter was introduced to quantitatively evaluate the reinforcement effect. The test shows that when the axial strain is less than 2%, the strength of the reinforced soil does not change significantly. As the axial strain continues to increase, the strength of the reinforced soil gradually exceeds that of the pure soil sample, and the large principal stress difference is the largest at 400 kPa confining pressure Increase by 50%; Through the quantitative analysis of the reinforcement effect, it is found that under the same confining pressure and the same number of layers, the gabion reinforcement strength is generally higher than that of the grille reinforcement, and the reinforcement effect coefficients are all above 1.39; Although the reinforcement can significantly increase the peak strength of the red sandstone and the ductility of the soil, and greatly increase the cohesion of the red sandstone, the increase in the friction angle is not large. Finally, the Duncan-Chang model and discrete element software are used to describe and verify the mechanical properties of the reinforced soil.