The lacustrine sediments deposited between the present water level and the high perched lake shoreline in Lake Jiezechakalocated in the northwestern Tibet provided good records of the lake evolution history. The three U series ages of the lacustrine sedimentsalong the bank are 14.2±1.2kaBP, 38.0±3.5kaBP and 41.6±3.2 kaBP, respectively. The contents of CaO, MgO, NaCl, LiCl and B₂O₃ in sixshallow wells are related to the age and environment when the sediments were deposited. In the end of middle Pleistocene, the lakeshoreline lied in the high perched position probably. From the early period of the Late Pleistocene, the levels of the lake began fallingbecause of the dry climate. The lake shrank gradually and the salinity was increased. Ca and Mg also increased correspondingly. However,around 30kaBP, there was a short wet period when the lacustrine water became less salty. Then, the lake water was further condensed withthe increases in the content of Na, B, and Li significantly. The present salt lake was formed at about 15 kaBP.