The extremely hot days during last 52 years(1951-2002) are investigated by means of statistical and wavelet analysis. The results show that extremely hot days mainly occur in the western, northern and southern Shandong province from May to August, mainly in June and July. They emerged frequently between 1950′s and the early 1970′s.In addition, the result of wavelet analysis indicates that the main period is about 4- and 10-years. The warm ridge in westerlies should be basically blamed for the most extremely hot days, and the subtropical high might play the second important role. Extremely hot day generally follows the previous hot days. And the warm center of 24℃ around Zhengzhou over 850hPa is a remarkable index for prediction of extremely hot days.