[Objective] We aim to investigate the effects of gravel content on soil erosion and water hydrodynamic characteristics of steep slope project.[Methods] The relationship between soil erosion change rate and soil erosion rate and hydrodynamic parameters was studied by means of indoor simulated rainfall experiment and artificial soil preparation, at 50° engineering slope with 5 kinds of gravel content(3%, 15%, 35%, 55%, 75%) under 3 rainfall intensity(40, 60, 80 mm/h).[Results] ① With 40, 60, 80 mm/h rain intensity, the slope runoff rate of each gravel content was decreased by 10.1%~55.9%, 13.9%~41.9%, 19.6%~47.7% compared with that of soil slope. Runoff shear force, runoff power and unit energy of runoff section showed a linear, exponential and power function relationship with gravel content, respectively. ② The erosion rate of slope decreased with the increase of gravel content, and the amount of erosion rate and the change process of different experimental rain intensity showed obvious difference. When the rain intensity was 40 mm/h, the overall sediment yield of the slope was low, and the rainfall duration showed a slow increase trend. When the rain intensity was 60 mm/h, the erosion rate increased rapidly under different gravel content, and then fluctuated. When the rain intensity was 80 mm/h, the gravel content was 3%, the growth rate of slope decreased rapidly after rapid growth. And when the gravel content was greater than 15%, the slope erosion rate began to decline slowly after reaching the peak value. ③ The soil erosion rate showed a significantly linear function, logarithmic function and power function relation with runoff rate, runoff shear force, runoff power and the unit energy of the water section of the project slope.[Conclusion] The soil gravel of engineering slope has anti-erosion effect, and with the increase of gravel content, the soil erosion amount and the hydrodynamic parameters of slope are reduced significantly.