Abstract:Abstract: Slope farmland is one of the most important parts of cultivated land resources for agricultural production in mountain and hilly areas. The type of land resource is also closely related to regional water and soil ecological protection, even food security. Among them, the soil erosion of slope farmland has been one of the most serious sources of regional erosion and non-point source pollution, due to the natural conditions and man-made unreasonable utilization. Particularly, soil erosion is generally accompanied by the loss of soil, nutrients, and water in the sloping farmland. As such, the thinner arable layer can reduce the nutrients of soil structure and the quality of cultivated land. It is a high demand for the quantitative evaluation of the distribution of soil erosion in the regional sloping farmland, particularly for the decision-making on the soil and water loss for the high-quality slope farmland. However, there are only a few studies on soil erosion and nutrient loss of slope farmland at the provincial scale at present. In this study, the Universal Soil Loss Equation (USLE) model was selected to quantitatively evaluate the characteristics of soil erosion and nutrient loss of sloping farmland in Yunnan Province of China. The GIS spatial analysis was also carried out to verify the parameters and accuracy of the model. The results showed that: 1) The soil erosion area of slope farmland accounted for only 22.95% of the total erosion area, but the amount of erosion was as high as 376.57×106 t/a, accounting for 63.02% of the total erosion in Yunnan Province. The slope farmland was the main source of erosion and sediment yield in the study area. The average erosion modulus of slope farmland was 7 986.31 t/ (km2. a) at the level of strong erosion. Severe erosion, extremely strong erosion, and strong erosion were the main sources of erosion and sediment yield of slope farmland. 2) The average erosion modulus of slope farmland increased rapidly with the increase of slope gradient. Correspondingly, the erosion intensity grade evolved from mild to severe erosion. The 3°-5° and 5°-8° slope farmland were mild erosion, the 8°-15° slope farmland was moderate and strongly erosion, the 15°-25° slope farmland was very strongly erosion, and the >25° slope farmland was the severe and very strongly erosion. The amount of soil erosion was often from the 15°-25°, the >25°, and the 8°-15° slope farmland. 3) The thickness of the lost soil layer in the sloping farmland was concentrated between 0 and 12 mm/a, and the average value was 7.31 mm/a. The renewal cycle of the cultivated layer was concentrated between 20 and 200 a, with an average of 175.6 a. The area distribution curve of the cultivated layer renewal cycle showed a rapid increase at first, then decreased rapidly after reaching a certain peak, and finally changed slightly with the increase of the cultivated layer renewal cycle. 4) There were some differences in the spatial distribution of nutrient loss in the sloping farmland. The loss modulus of Soil Organic Carbon (SOC), Total Nitrogen (TN), Available Potassium (AK), and Available Phosphorus (AP) in the sloping farmland were 223.60, 23.94, 1.59, and 0.15 t/(km2·a), respectively, which was 4.34-5.50 times of the whole province. Therefore, the sloping farmland can be the main source of nutrient loss in Yunnan Province of China. The research can also provide the scientific basis to control the soil and water loss for the high quality of regional slope farmland.