In August, 1999, w e investigated Golmud River-Dabsan Lake field and sampled systimatically from surface water along the river from the source-Kunlun Moutian to the end-Dabsan Lake.After that, we analysed the principal chemical composition of the river water and calculated some parameters such as mineralization, and types of hydrochemistry and so on.According to the fluctuation of mineralization along the river from south to no rth, five different reg ions may be distinguished:(1)region Ⅰ:gobi;(2)region Ⅱ;alluvial-pluvial fan;(3)region Ⅲ:alluvial-pluvial plain;(4)region Ⅳ:lacustrine plain;(5)region Ⅴ:brine lake, among which region Ⅱ can also be divided into two sub-regions:(Ⅱ₁)the part of w est river of alluvial-pluvial fan and (Ⅱ₂) the part of the east river of alluvial-pluvial fan.From region Ⅰ to region Ⅴ, the mineralization increased as a w hole.There appears an abno rmal high value in sub-region Ⅱ₂, due to the disturbing as the shallow g round w ater has relatively higher salt content.The g round water level is so shallow as to reach the surface of earth, a great amount of salts w ere dissolved from soil by shallow phreatic water and then flowed into river, which made primitive fresh river water became half brine, the type of hydrochemistry changed suddenly from C_Ⅱ^Na to C_Ⅲ^Na.From this region tow ard the lake, the river discharge had no great change except for region Ⅲ.The hydrochemistry of region Ⅳ w as nearly the same as in the region Ⅲ except that the mineralization w as somew hat lower.As fo r region Ⅴ, the Dabsan Lake became a brine lake due to its long histo ry of evolution.Origionally the region Ⅴ was a play a as a dissolution basin.Under the condition of ex treme arid climate as w ell as high evaporation a brine lake came into being. Generally, the hydrochemistry of west river w as more stable than that of the east river.The adjustment capacity of west river w as better and does no t easy to be disturbed by other water.In the long run, future harnessing of water resource should lay stress on the part of the west region, mean while some measures should be taken to keep the half brine water of east river from any further salilization.