Bosten Lake is the largest lake in Xinjiang at China, which lies of the southeast of Yanqi Basin (86° 20' E to 87° 26' E,41° 44' N to 42° 14' N） and has the arid desert climate. Kaidu River is the longest river which flows into Bosten Lake, and its average annual runoff is 35.06 x 108 m3/a in the upper reaches from 1958 to 2012, accounting for over 80% of the total recharge of Bosten Lake. Therefore the water quantity and water quality of Bosten Lake is chiefly controlled by the runoff of Kaidu River,and also affected by the amount of water diverted from Kaidu River Irrigation Area. As the biggest freshwater lake in the inland China,the water resources is very important for the irrigation agriculture and the ecological environment. However, it has become a slight salt lake currently due to the impacts of human activities and climate change since the 1950s, and ecology and environment have degenerated. In this paper, they were analyzed on the materials of lake inflowing, temperature,precipitation and runoff in the Dashankou by using the Mann-Kendall trend test method and wavelet analysis method. Results showed that change of precipitation, temperature and runoff in the upper reaches of the Kaiduhe River (Dashankou station) increased significantly (passed P< 0.001, P< 0.01 and P< 0.01, respectively),while the inflowing runoff of the lake increased a little with an not significant trend. For the salt influx of the lake,the salt mainly came from the Kaidu River and the farming drainages ; For the salt efflux,the annual salt amounts depended on the discharges and the salinities of the outflows water, which were partly controlled by humanactives through the irrigation works such as the water canals,the pump station at the lake etc. In theory,from the average case for many years,lakes water demand under the design scenario 1 anddesign scenario 2 on salinity goals were 12.62 x 10~8 m~3 and 14.28 x 10~8 m~3, respectively, corresponding to the absolute water level 7.25 m and 7.70 m, respectively. In recent years, although there was exporting salt in an accumulation of average 30.6 x 10~4 1 · a~(-1) that made desalination in the lake, but mineralization degree of the lake is still higher, so increasing freshwater and decreasing input-salt to improve the lake water quality is still an effective way. This paper attempted to analyze the relationship between water quality (mineralization degree) and water quantity by mathematical statistical methods and water demand is discussed under natural conditions in the study area,which provide scientific guidance for human activities within the basin,and better management of the surface water resources and decreasing the effects of human activities were necessary to make sure the enough water quantity of Bosten Lake,in order to protect the ecological environment,and make sustainable development of agricultural production and rational allocation of water resources.