In the gully and hilly areas of Loess Plateau, with the cropland being returned to woodland or grassland, it is sure that the characteristics of soil erosion will be influenced greatly. To provide theoretic basis for the above-mentioned policy, it is necessary to simulate the effects of the cropland returning on soil and water loss. In this paper, part of Ansai county was selected as the test area, which is located in the gully and hilly areas of the Loess Plateau. By use of the USLE combined with RS and GIS, the effects of cropland returning on soil erosion were simulated. Based on the land use pattern in 2001, 8 cropland returning scenarios were designed. The results indicate that the soil losses from areas where intensive erosion or more intensive erosion occurs decreased most markedly. For all the cropland returning scenarios, there are no areas where severe erosion occurs and the soil losses from areas where intensive erosion and very intensive erosion occur decreased markedly. Of all the cropland returning scenarios, 25° or more steep cropland returning and 15° or more steep cropland returning are the scenarios under which the total soil losses decrease most markedly. Under the scenarios of 25° or more steep cropland being returned to grassland and to woodland, the total soil losses decrease 19.9% and 23.2% respectively; under the scenarios of 15° or more steep cropland being returned to woodland and to grassland, the total soil losses decrease 36.6% and 42.6% respectively. Compared to the scenarios of 15° or more steep cropland returning, there is no marked difference in terms of the effects on soil erosion under the scenariosof 15° or more steep cropland returning and all cropland returning.