Abstract: To solve the problem of soil erosion on the side slope of the highway, the purpose of ecological protection of the slope was achieved. Relying on a practical project, based on Mohr-Coulomb's bullet plasticity theory, the highway slope model was constructed by using MIDAS GTS NX software. Combined with the strength reduction method to analyze the ecological light pile shear stress and distance, and shear stress difference and distance change law, different directions of shear were built. The relationship between stress difference and solid soil distance was compared to the solid soil distance, and the solid soil distance of ecological light piles in slope vertical, horizontal upper, horizontal lower, oblique upward and oblique downward was 0.45, 0.40, 0.72, 0.44, and 0.64 m, respectively. According to the ecological light pile solidification model, relying on the principle of the greatest solid soil strength, the optimal solid soil distance of ecological light pile was determined to be 0.4 m and the optimal pile spacing was 0.8 m. A new idea was put forward for the reasonable design of ecological light pile spacing on the highway slope.