As glaciers recede in response to the significant warming on the Qinghai-Tibetan Plateau (TP) since the 1950s (0.16°C per decade [1]), the number and size of glacial lakes increase rapidly and cause more Glacial Lake Outburst Floods (GLOFs) in the Himalayas, aggravating risks to people and towns in downstream regions. To better understand this geo-hazard, it is necessary to evaluate the evolutionary history of large glacial lakes on the TP. Glacial lakes often expand/shrink in accordance with the changes of controlling glaciers and lake level is generally regulated by a combination of monsoonal precipitation and glacial meltwater, providing a record to study the history of glacial meltwater and regional paleo-climate change. However, for glacial lakes, geomorphic features like the paleo-shorelines are rarely preserved due to the frequent glacial movement, therefore it is hard to reveal past lake levels. In this study, we investigated the Ranwu glacial lake in the southeastern edge of the Tibetan Plateau, at the north slope of the Himalayas. Based on OSL dating of a series of fluvial and lacustrine sediment profiles, using both quartz OSL and K-feldspar pIRIR signals, we attribute that the ages and elevations of these outwash sediments can be used to provide a conservative estimation for past lake levels of the Ranwu Lake. The results suggest the following: (1) The recent highest lake level for Ranwu Lake should has an elevation exceeding 4,380 m (+460 m above the modern lake). The pIRIR (50, 225) age from K-feldspar is about ~50-70 ka, implying a large glacial lake with high water level once existed; (2) After that, the lake level gradually dropped until ~30 ka, then followed by a rapid drop of ~300 m during ~30 to ~20 ka, possibly linked to the arid climate in the last glacial maximum. (3) Then, the lake level remained relatively stable after 20 ka. Other factors including regional neo-tectonics, basin topography and water outlet have also been discussed. [ABSTRACT FROM AUTHOR]