Abstract: In this paper,the characteristics of summer drought in recent 30 years were analyzed using the EOF and REOF methods based on the monthly precipitation and evaporation data and the calculated and drought K  index at 7 meteorological stations in Altay,Xinjiang during the period from June to August from 1981 to 2010,and the maximum entropy spectrum and the harmonic analysis were used to analyze the major cycles of the drought K  index in three regions of Altay.The results showed that,according to the drought [WTBX]K[WTBZ] index,the drought occurring frequency in the western and central regions was higher than that in the eastern region of Altay.The study area could be divided into 3 regions,i.e.the southwestern valleyplain region (region Ⅰ),eastern hilly region (region Ⅱ) and northern mountainous region (region Ⅲ).Summer drought intensity in these three regions was holistically in a decrease trend.The spatial distribution of drought was affected by not only the largescale weather system including precipitation change,but also by many other factors,such as geographical location and terrain.There were the relatively stable 10year and 3-5year fluctuations of drought,but their main periodic and annual changes were significant.

Key words: drought K index, meteorological drought, summer drought, spatial distribution, Altay, Xinjiang