Abstract: To explore the spatio-temporal variation and driving force for water area on land surface in the Ili River Basin, and to provide a basis for the right confirmation and allocation of transboundary water resources, the global surface water dataset was used to study the spatio-temporal variation of land surface water area in the Ili River Basin from 2001 to 2020,during which the precipitation, temperature and land use data were taken into consideration.The results showed that:(1) The land surface water area in the Ili River Basin increased by 661 km2 from 2001 to 2020,the growth mainly located in the southern part of Balkhash Lake outside China and the basin inside China.(2) In the past 20 years, the number of water range larger than 1 km2 increased by 41 while that of larger than 5 km2 increased by 14.The water area of Balkhash Lake showed a fluctuation of increasing and then stabilizing, and the water area of Kapchagay Reservoir showed a declining trend.(3) The land surface water area inside China was rarely affected by climatic factors, the alteration of land use types was the dominant factor causing the change of water range.The change of arable land area was the dominant factor affecting the waters range outside China.The research results can provide scientific support for land use planning and rational allocation of water resources in the Ili River Basin.