According to the observed data during 1950 - 2010,the authors analyzed water and sediment relationship of 6 major hydrological stations of the valley in the desert on the upper reach of the Yellow River,the water and sediment source spatial distribution,and its influence factors at the Toudaoguai hydrological station. The results show that: ①The runoff of Toudaoguai hydrological station mainly come from the area above Lanzhou,and the sediment mainly from Lanzhou to Toudaoguai section tributaries. Compared with the ference period from 1950 to 1968,the average runoff of Toudaoguai station from 1969 to 1986 and 1987 to 2010 were reduced by 10. 1% and 40. 6%,and the average annual sediment decreased by 37. 2% and 75. 4% respectively. ②The runoff reduction of Ning-Meng reach mainly occurred in Shizuishan to Bayangol River,to reduce the average annual runoff of 5220 million cubic meters. The sediment reduction of Ning-Meng reach mainly occurred in Qingtongxia to Bayangol River,in which the average annual sediment decreased by 24. 4 million tons. There is an increasing trend of unit water sedimentation with the increase of the average annual sediment coefficient at Toudaoguai hydrological station in Ning-Meng reach. The basic balance incoming sediment coefficient is about 0. 0023kg·s /m~6. Climatic fluctuations,the Longyangxia and liujiaxia reservoirs adjusting,industrial and agricultural water use,comprehensive management of soil and water conservation re the main factors that influence the spatial distribution of water and sediment source at Toudaoguai hydrological station.