Abstract: Understanding regional water and sediment transport patterns and their responses to climate and land use changes can provide a theoretical basis for the prevention and control of soil erosion, and is an important prerequisite for the integrated development of land and water resources. Based on monthly monitoring meteorological, runoff, and sediment data from 1963 to 2013, combined with the land use data in the 1980s and 2000 and NDVI data, using the Mann-Kendall trend analysis and abrupt change test method, we systematically analyzed the long-term variations of the climate, runoff and sediment transport, with the changes of land use and vegetation coverage being identified in the Xiaonanchuan (XNC) River basin, a typical watershed in the Northwest arid region. Based on the analysis of single element change, the impacts of climate and land use change on water and sediment transport were quantified by the multiple linear regression analysis. Simultaneously, the key action factors were identified. Results showed that air temperature was developing to the polarization, the precipitation increased gradually. A generally warm and wet tendency of climate change and an increased frequency of extreme climate events were found in the XNC River basin. Moreover, the speed and magnitude of climate change were intensified after the 1990s, which was the abrupt change point of the climate. Since the 1980s, with economic and social development, the area of arable land and built land expanded, that of the forest area increased, and the ecological environments were improved in the XNC River basin. Under the dominant driving effects of land use and vegetation coverage change, the runoff and sediment load gradually reduced with the average rate of 1.7×10⁶ m³·(10 a)^-1 and 1.5×10⁸ m³·(10 a)^-1, respectively. Quantifying the influence of land use and climate change on the water and sediment transport indicated that vegetation cove-rage and mean daily maximum temperature were the two key factors affecting the runoff change, while the vegetation coverage and maximum daily precipitation were the two key factors affecting the sediment load change. Under the condition of current climate change, ecological restoration could be one of the most effective ways to prevent water and soil losses in the arid area.