The plateau lakes are sensitive indicators of climate change. The variation of lake area were monitored by using multi-source satellite data from 1976 to 2017 in the Qaidam Basin. The results show that the climate of the basin had been warming and humidifying in the 50 years,especially since 2000. The rising rate of annual average temperature had increased from east to west,and the increasing rate of precipitation had decreased from east to west. The Torsu Lake in the eastern part of the basin had less decreased from 1956 to 2017,with a rate of-0. 41 km~2·a~(-1) . However,during the period of 2005-2017,the lake surface had expanded at a rate of 1. 34 km~2·a~(-1) . The area of Xiaochaidan Lake in the basin middle had increased 19. 87 km~2 as compared with that in the past 13 years; while the area of the western Gaskule Lake had increased first and then decreased. Climate change,variations of vegetation area and lake runoff and human activity are the main causes of lake area change in Qaidam Basin.