A largescale drought and high temperature weather occurred in the rainy season (July and August) of 2006 over Shanxi Province, resulting in severe drinking water difficulty and agricultural disasters. Particularly, there occurred much less heavy rainfall processes in the usual rainy period from July 21 to August 10 of the year. It seldom occurred in history. The data of atmospheric circulation at 500 hPa and the indexes of subtropical high are analyzed and primary causes mainly include the activity of cold air, the location of subtropical high, the disposition status of weather systems and so on.