Abstract: By using the method of rotated empirical orthogonal function(REOF) and according to thunderstorm days data of 113 routine meteorological stations,Yunnan Province is partitioned into six regions and its spatial-temporal variation is analyzed.The results showed that the thunderstorm days in Yunnan Province had a descending trend during1961—2006,and thunderstorm days took place an abrupt occurred in1980s.For spatial-variation,all of various regions had descending trend,especially in Southern Southwestern Yunnan.Initial/ending dates of thunderstorm had ahead trends and the number of days between two dates had an increasingly trend,but don't attain marked levels of statistics.