Abstract: Rill erosion can be defined by concentrated flow in small rivulets. This type of water erosion has posed a great challenge on the sloping cropland on the Loess Plateau in China. Most previous studies were focused on the field or laboratory experiment, while the research on rill erosion under conditions of extreme heavy rain is still lacking, particularly on practical prediction on specific cropland. The purpose of this study is to investigate the characteristics of rill erosion on long and steep slopes under extreme rainstorms based on field survey data. After the heavy rainstorm on the central Loess Plateau on July 26, 2017, 15 sampling sites were selected based on Google imagery near the rainstorm center with event rainfall of 212 mm and the maximum 60-min rainfall intensity of 49.2 mm/h for rill erosion measurement. In each sampling site, cross-sectional properties were measured at 2-m intervals, and the width and depth of each rill in each section were recorded. Topographic parameters were measured based DSM derived from drone aerial images in 0.20 m resolution. Rill erosion data from a previous study on five plots under storm conditions were used to compare the impact of rainfall intensity on rill erosion along slope length. The results showed that: 1) Under rainstorm conditions, the rate of rill erosion on bare sloping cropland was 22 487 t/km2, and that on sloping cropland accounted for 68.6% that of the bare land, as the slope length was 20 m. Contouring cultivation can reduce effectively erosion, where the rill erosion was less than 5% that of the bare land, but the downslope rill erosion still occurred. The rate of rill erosion on fallow cropland was only 12% that on bare cropland with the same slope gradient, and no rill erosion was found on grassland. 2) The power function, Er=aLb, can fit the relationships between the rill erosion rate and slope length. The index of slope length (b) was 0.831 for the bare land with the slope gradient of 34°. The index of slope length increased as the increase of the rainstorm intensity, indicating that the rate of rill erosion enhanced under heavy rainstorm conditions. 3) Most sloping croplands on the loess hilly region are located in the middle of hillslope, and there is a steep ridge with 1-2 m high between the cropland and uphill grassland. Upslope contributing runoff can cause severe rill erosion on the sloping cropland. Specifically, grassland with a length of 38m can lead to the maximum erosion modulus on the downslope cropland, 56 304 t/km2. However, there was no a clear increasing trend in the rate of rill erosion as the increase of slope length, indicating that the upslope runoff has a greater impact on rill erosion than the rainfall received on the site. The existence of ephemeral gullies on the slope reduced the rill erosion intensity due to the confluence capacity of the ephemeral gullies. The finding demonstrated that the more severely the ephemeral gullies was developed, the less the rill erosion intensity was. This study can provide an important reference to estimate the rill erosion on different types of sloping land in the hilly area of Loess Plateau.