Lakes on the Tibetan Plateau, which are rarely influenced by disturbance of human activities and mainly controlled byglacier melting and evaporation caused by climate change, are a typical study area of global climate and environment change. Re-mote sensing technology to monitor lake changes across the plateau has important significance to global climate and environmentchange research. This paper developed an iterative modern lake extraction method on remote sensing images using index calculationand spatial difference comprehensively, to detect lake changes dynamically; and developed a semi-automatic paleo-shoreline extrac-lion method combined with DEM, so as to analyze paleo-lake change. Combining the two methods, we can clearly and completely getthe lake changes across the Tibetan Plateau since the ancient and modern ages. Finally, we task Dagze Co as an example to proceedwith the methods, and analyzed its shrinkage conditions since the latest 25 years and since the Great Lake Period.