Based on the average annual water level data of Issyk-Kul Lakefrom 1950 to 2010,using trend analysis and Morlet Wavelet analysis to study the Issyk-Kul Lake average annual water level, which reveals the overall trend and periodic variation regularity of water level of Issyk-Kul Lake. The results show as follow-ings: (1) Water level presented overall downward trend, decline in total 1. 27 m in the period from 1950 to 2010,water level continued to decline from 1950 to 1997,water level began to rise in 1998. (2) Before the 1990s,human activities are the main driving factor causing the lake level decline, the increased precipitation of the region increased runoff due to the role of global climate change,causing the water level to rise slowly. (3) Results from the Periodic analysis of 19502010 showed that Issyk-Kul Lake water level change primary period was 21-year, and the period of time Issyk-Kul Lake water level remain rising after 2010.