Abstract: In order to study the influences of bedrock exposure rate and soil thickness on water and soil loss in karst areas, the simulation experiments are carried out to study the hydrological process and its driving water and soil movement process by the self-made test equipment. Considering the phenomenon of soil surface loss/underground leakage under karst hydrogeological structure, the results show that the characteristics of surface and underground soil loss rate are that the runoff rate rises rapidly to the peak value and then gradually decreases. There is a significant positive correlation between the soil underground leakage rate and the soil thickness, and a significant negative correlation between the soil surface loss rate and the bedrock exposure rate. With the increase of the bedrock exposure rate, the fluctuation of soil surface loss rate with time is more obvious. The correlations between the sediment yield and the bedrock exposure rate/soil thickness are fine, and the linear correlation coefficients R² are all above 0.9. The surface sediment yield decreases with the increase of the bedrock exposure rate and soil thickness, and the underground sediment yield decreases with the increase of the bedrock exposure rate but increases with the increase of the soil thickness.