Abstract: The basic climate characteristics of Guangzhou's thunderstorm diurnal change are analyzed. The conclusions are as follows: Guangzhou's thunderstorm mainly occurs from May to August, with the its proportion to annual thunderstorm being 71.38 % and having the characteristics of two peaks of its seasonal distribution. The trend of total thunderstorm in Guangzhou city is descending. The relationship between thunderstorm days from May to August and corresponding 850 hPa atmospheric circulation is that: In more thunderstorm years obvious westerly exists in the middle latitude of Asia, southwesterly and southerly wind in the area of South China Sea and Guangdong and their extended northward region; in less thunderstorm years things are just the opposite. A simple correlative analysis of SST over offshore waters in China points out that negative correlation between thunderstorm and April～June SST over western Pacific near Indonesia is found.