Glacial lakes play an extremely important role in the fragile plateau eco-environment because they are sensitive indicators of climate change in alpine cold areas and can be a source for mountain outburst flood or cause mudflow disaster. Based on multi-source remote sensing image data (Corona, Landsat MSS/ TM/ ETM+/ OLI) from the 1960s to 2010s, topographic maps in the 1970s, glacier inventory and meteorological data, we performed a comprehensive assessment of the spatial-temporal variations of glacial lakes (≥0.05 km2) in the Koshi River basin and examined their influence on glacier changes. The major results of these studies are as follows. First, the area of glacial lakes in the Koshi River basin remained constant between the 1960s to the early 1980s before rapidly expanding between the mid-1980s and early 2000s. The most rapid expansion was observed after the 2000s. Second, the lakes were centrally distributed in altitude band of 5000—5500 m in this river basin. Glacial lakes with an area of 0.05—0.25 km2 constituted the highest proportion of lakes (74.45%), and the largest area was covered by 0.05—0.25 km2 and above 1 km2 lakes (64.18%). Third, the glacial lakes in each sub- catchment of the Koshi River exhibited a trend of expansion, with the exception of the Likhu Khola basin. Furthermore, there were significant changes in the areas of glacial lakes in the Arun basin. Climate warming and glacial retreat are the main causes of glacial lake expansion in the Koshi River basin. Furthermore, when the terminus of a glacier extends into a glacial lake, there is a significant exchange of matter and energy. We infer that this may accelerate ice melting and the consequent glacier retreat. © 2017, Ecological Society of China. All rights reserved.