Abstract: Abstract: Land use/cover change (LUCC) is a key component of global climate change, and it has great impacts on climate, hydrological processes, biodiversity and ecological processes. Therefore, more attentions have been paid to LUCC. As land use pattern is significantly influenced by topographical factors that indirectly has impacts on water and surface energy balance, analysis of land use pattern is thus a useful method to assess the rationality of LUCC according to the variations in their topographic factors, which will further provide important information for land use management and soil conservation. Fen River Basin is one of the regions with most severe soil loss on the Loess Plateau, and it has been experiencing great changes in land use pattern due to the implementation of soil conservation measures. After using land use data of 1986, 1995, 2005 and 2010 to analyze the temporal and spatial variation in land use from 1986-2010, and using terrain niche index derived from DEM (digital elevation model) to represent the topographical factors of different land use patch, the relationship between terrain and land use change was systematically analyzed. Results showed that from 1986 to 2010, the main land use types of the study region were farmland, forest and grassland, which account for 94% of the whole catchment, and the main land use change types were the decrease of farmland and the increase of urban and residential land. The rate of land use change for the period of 1986-1995, 1995-2005 and 2005-2010 were 13.2%, 25.8% and 36.4%, respectively, indicating a speed-up land use changes. But for the whole study period, the land use change rate was 1.3%, which implied that the land use pattern was recovering the original status with less human disturbance. Our results also showed that the spatial distribution of land use types had close relationships with terrain gradient. The farmland, urban/residential land and water sources were mainly located in the areas with low terrain gradient, while grassland in the areas with middle terrain gradient and forest in the areas with mid-high terrain gradient. According to the land use change TUPU, we found that the primary land use change types were stable type and repeated change type, which accounted for 98.4% of the whole catchment. The stable land use change type was mainly composed of forest with large terrain gradient and farmland with small low terrain gradient, while the repeated change type mainly from the mutual conversion between grassland and farmland at areas with mid-low terrain gradients. In addition, the results indicated that LUCC in the Fen River Basin was the combined effect of natural processes, human activities and government policies. The natural processes played a key role in the impacts of terrain gradient effect on land use change, while human activities and policies were very important drivers that can make land use change rapidly in a short time period. Overall, the land use pattern in the Fen River Basin has been becoming rational. However, some improper land use change types were also detected. Based on analyzing the rationality of land use change by topographical factors, this study was meaningful to the sustainable development of land resources, and it can provide important information for land use management in the Fen River Basin.