Hydraulic erosion indoor experiments are conducted by considering the soil erosion of the iron tailings pond and the restoration of the ecological environment of the reservoir area. The time-varying law of runoff modulus, the time-varying law of erosion modulus, the rate of total infiltration and vegetation interception and full interception of vegetation of the tailings pond slope are studied under the four working conditions of tall fescue, star grass, bison grass and bare slope. Based on the indoor direct shear test of root-tailing sand complex, the variation of cohesion and internal friction angle of buffalo root-tailing sand complex under different root contents and growth times are studied. Furthermore, the effects of root content and growth time of the buffalo grass on the erosion resistance of iron tailings sand are analyzed. The optimum root content and root growth time of the root-tailing sand shear strength and slope erosion resistance are determined. The results show that the buffalo grass is the preferred grass species in the soilless vegetation slope protection project of iron tailings reservoir. The buffalo grass root serving as the reinforcement material of iron tailings sand can dramatically improve the cohesive force of tailings sand and the slope erosion resistance. The cohesive force of root-tailing sand gradually increases and then decreases with the increase of root growth time and root content, which is always higher than that without buffalo grass. The optimal growth time of the buffalo grass is three months, and the optimal root amount is about 0.20%, which has little effect on the internal friction angle of iron tailings reservoir.