A statistical analysis is made of the daily observation data of thunderstorms from 10 weather stations in Yili from 1959 to 2008; the variation regularity and features of thunderstorm days are summarized; and regional division is conducted. The results show that the Yili area is one of areas attacked most frequently by thunderstorms with the annual mean number of thunderstorm days being 175 to 861 days, but the total trend of thunderstorm days reduces gradually with interdecadal oscillation. Thunderstorms start to occur from the last 10 days of February, most frequently between March and November, and end in the second 10 days of November. There seldom occur thunderstorms in January and December in Yili. Monthly mean thunderstorm days gradually increase from March to June and decrease from July to November. Yili can be divided into four areas according to lightning protect grades: Grade 1,Zhaosu County;Grade 2, Tekesi County;Grade 3,Yining, Nileke, Huocheng, Huo’erguosi port, Gongliu, Xinyuan County; Grade 4,Yining County, Chabucha’er County.