Abstract: By using the data of thunderstorm of Shandong Province from 1966 to 2005 and applying EOF method and other mathematical statistical methods, the characteristics of spatial-temporal variations of thunderstorms were studied. The main results are as follows: the distribution of annual mean of thunderstorm days shows that thunderstorms in the mountainous areas of Mt. Taishan and Mts. Yimeng are more than ones in the western plain area of Shandong Province and coastal region of Shandong peninsula. Thunderstorms mainly occur in summer with obvious diurnal variation. Analyses indicate that the general trend of Shandong thunderstorms has wavily reduced during the last 40 years .The interannual and decadal variabilities of thunderstorms are obvious in Shandong Province.

Key words: EOF analysis, thunderstorm days, spatial-temporal variations, interannual and decadal variabilities