<p>The Selin Co basin contains the largest endorheic lacustrine system in Xizang, comprising a closed lake group of more than 20 lakes. In recent years, the sustained expansion of Selin Co has had significant impacts on local human settlements and ecosystems. Based on long-term remote sensing imagery and high-resolution meteorological data, lake areas were extracted using the normalized difference water index (NDWI), indices were developed to characterize lake response synchrony and regulation capacity, and the differential responses of terminal lakes and flow-through lakes to climate change were compared. Results indicate that the region has experienced a pronounced warming and wetting trend. Since 1988, the warming rate has been 0.4 °C (10 a)⁻¹, precipitation has increased at a rate of 25.0 mm (10 a)⁻¹, and the total lake area has expanded by 25.2%. Most terminal lakes exhibited an expansion trend, with Selin Co showing the most pronounced increase (42.9%). Its expansion process can be categorized into three stages: slow expansion (3.4 km² a⁻¹) from 1988 to 1999 under relatively low precipitation and temperature; rapid expansion (36.5 km² a⁻¹) from 2000 to 2013 with substantial increases in precipitation and temperature; and continued but decelerated expansion (7.9 km² a⁻¹) since 2014, as the rising trends of precipitation and temperature weakened. In contrast, flow-through lakes show smaller interannual variations in area (&lt;5%) and higher synchrony. Annual maximum lake areas are typically observed between August and October. The six large flow-through lakes upstream of Selin Co have a combined retention capacity of 160–360 million m³ (approximately 240 million m³ on average), playing a critical role in flood peak attenuation and flow regulation.</p>