show that the water level of Balkhash Lake exhibited obvious periodic variations between 340~344 m during 1879-2015， and the change period was between 48~52 years. A significant upward trend was detected for the water level from 1988 to 2015， with an increasing speed of about 6.91 cm/a. A decreasing trend was observed for runoff from major rivers flowing into the lake； among them， the amount of water from the Ili River accounted for about 80% with an upward trend. Also， The Ili River's runoff flowing into Kazakhstan from China has been increasing， suggesting that the water utilization in China does not cause the decrease in the lower stream of the Ili River. The first water storage of the Kapchagay Reservoir directly lead to a sharp decrease in runoff in in the lower reaches of the Ili River， which eventually caused a significant downward trend in lake levels. During this period， the lowest level was about 340.68 m in 1987， suggesting a decrease of nearly 2.3 m. Since the Soviet period， agriculture land of the Balkhash Lake Basin has undergone four periods： increasing period， decreasing period， increasing period， and stable period， and the expansion of agricultural land and water conservancy projects in the middle and lower reaches of Kazakhstan resulted in a decrease in the amount of water flowing into the lake from the Ili River.

obtained from this study could offer a useful reference for the rational utilization of water resources and ecological environment protection in the Sino-Kazakh cross-border river basin.