Abstract: Slope cropland erosion is the most serious land degradation problem in plateau mountainous areas. A great threat has been posed to regional food security and sustainability of agriculture. Particularly, the Wenshan Prefecture of Yunnan Province is characterized by serious soil erosion in China. Taking the Wenshan Prefecture as an example, this study aims to quantitatively evaluate the soil erosion of the farmland and spatial features using multi-source remote sensing data, such as the Third National Land Survey, Water Conservancy Sampling Survey, and the Wide Field of View (WFV) imaging system of GaoFen-6 (GF-6) satellite. Firstly, the non-cultivated land was masked in the GF-6 image with the Third National Land Survey data. The sampling units were also used as the sample set. Secondly, object-oriented multi-scale segmentation was performed on the GF-6 image, where the Jeffries-Matusita distance was adopted to determine the preferred feature set of spectral, texture and shape. Thirdly, Random Forest (RF) algorithm was employed to quickly and automatically extract the terraces. The fine rasterization of the E factor was realized to combine the engineering measures in the sampling units. Finally, the Chinese Soil Loss Equation (CSLE) model was utilized to conduct a fine quantitative assessment of soil erosion in the mountainous arable land. A spatial autocorrelation analysis was also carried out on the soil erosion features and influence factors in the GeoDa software in order to reveal the spatial distribution pattern. The results indicated that: 1) The distribution of arable land in the Wenshan Prefecture was bounded by the Guangnan, Xichou, and Maguan, indicating a descending pattern from the west to the east. There was about 6 252.85 km2 of slope cropland in the study area, accounting for 79.27% of the total arable land. The cultivated land was 3 929.57 km2 with the soil and water conservation engineering measures, accounting for 49.79% of the total arable land area. 2) Soil erosion modulus of the cultivated land ranged from 0 to 118 540.97 t/(km2•a) with an average erosion modulus of 5 180.72 t/(km2•a). About 69.99% of the total cultivated land was suffering from serious erosion. The total annual amount of soil loss from the cultivated land was 40.815 million tons, 20.60% of which was eroded from the land with the soil conservative measures. By contrast, the soil loss from the cultivated land without any soil conservative measures was 32.407 million tons, accounting for 79.40% of the total. There was also a significant difference in the response of erosion to the slope and elevation, particularly with the vertical zonal characteristics. The area and intensity of soil erosion increased first and then decreased, as the elevation and slope increased. The high incidence areas of erosion were found between the elevation zones of 1 000-1 400 m and 1 400-1 800 m, accounting for 27.23% and 50.54% respectively. The steep slope cropland (>20°) erosion also contributed 75.30% of the total erosion. 3) The spatial distribution of cropland erosion demonstrated outstanding aggregation characteristics and strong spatial correlations with the R and LS factors, respectively. Specifically, the Maguan, Malipo, Xichou, and Funing in the south of Wenshan were the high-value centers of erosion, and, the low-value centers were found in the Wenshan, Yanshan, Qiubei, and Guangnan in the central and western regions. The fine quantitative assessment of soil erosion was achieved to automatically extract the soil erosion factors on the regional scale for the spatial autocorrelation analysis. The finding can provide a strong reference to accurately allocate the regional soil and water conservation resources, as well as the ecological environment construction.