Based on MODIS09data,the lake areas were extracted from 2001to 2014in Qaidam Basin using Normalized Difference Water Index (NDWI)after we compared the results of 6 methods of water index. Combined with meteorological data and glaciers area variation,the impact factors of lake area change in Qaidam Basin were analyzed.The result shows that the lake area in Qaidam Basin increased first and then decreased. The number of lakes with area smaller than 1km~2 was the maximum.The lake area between 10and 100km~2, and area with larger than 100km~2 occupied 36%and 58%of the total area,respectively;they occupied a large portion of the total lake area.Most lakes were located at plain area with elevation smaller than 3000m.In the last 14years,the air temperature of the study area was at a high level and precipitation in the basin changed consistent with lakes change while the evaporation decreased slowly.Overall,the glaciers area and reserves in Qaidam Basin decreased slowly,and there was negative correlation between the variation of lakes and glaciers area.The increase of precipitation and decrease of evaporation and glacier melt are fundamental factors for the lake area change.