Qinghai Lake, the largest inland lake in China, is situated in the northeastern margin of Qmghai-Xizang Plateau.Because of the influences of natural factors and human activities in the past 30 years,the ecological environment around the lake has been rapidly deteriorated.The water level of the lake has iallen 3.35m and its surface area shrunk by about 300km² According to the investigations and the other data ob-tained,the mean water consumption from the lake is 4.36×10⁸m³ every year,and artificial water consumption reaches up to about 8.7% of the total,accounting for about 1% of evaporation of the lake surface.It is not evident that the artificial water consumption is relative to the water fluctuation.the decline of Qinghai Lake water level is due to synthetical factors,among which the main one is climatic change.The influence of human activities on the lake water level is shown through the eco-envfronmental deterioration around the lake.