In order to study the characteristics of runoff and sediment yield under different conditions of sloping farmland in Karst mountainous area, the development mechanism of runoff erosion and its influencing factors were analyzed by field rill erosion simulation experiment, and the sediment yield characteristics of runoff erosion process were studied in depth, the results show that: Under the same flow rate, the test area shows that the greater the slope, the higher the initial sediment concentration, and the surface sediment concentration decreases with the increase of rainfall time, only the sediment concentration of Hongfeng Lake is in a “double peak”. Under the flow rate of 5 L·min-1, the slope increases to 20°, which has a certain inhibitory effect on the runoff sediment concentration. Under the flow rate of 10 L·min-1, the sediment concentration increases with the slope, and There is a significant positive correlation with the slope, and the correlation coefficients are 0. 985, 0. 913, 0. 938, and 0. 910. At the test site in Naming district, the Kr value is the lowest and the erosion resistance is the strongest. For each test site, the overall sand content showed a decreasing trend with time, and there was a significant positive correlation with the slope, and the higher the clay content, the stronger the soil erosion resistance.