To assess changes in glacial lakes in the Chinese Himalaya, 2 inventory phases were conducted on the basis of 278 aerial survey topography maps from the 1970s and 38 Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images from the 2000s. In the past 30 years, the number of glacial lakes has decreased, from 1750 to 1680 (a decrease of 4.0%), whereas the average area of glacial lakes expanded from 166.48 to 215.28 km² (an increase of 29.7%). Between 3400 and 6000 m, glacial lake areas expanded at rates of 2–84% in almost all 100-m elevation bands, and the dominant expansion rates at different elevations were inversely correlated with glacier area retreating rates to some degree. Glacial lake expansion was a dominant contributor to the increase in glacial lake area, accounting for about 67% of the net changes in lake area, whereas newly formed lakes accounted for the remaining 33%.