Abstract:Based on the conventional data of daily temperature and of the NECP/NCAR reanalysis, the heat waves of China in summer of 2009 are studied. The results show: (1) high-temperature events occurred during the summer of 2009 over eastern China more frequently than the historical period, they concentrated in north China and south of the Yangtze River. (2) Continental warm high is the main circulation that led to the heat wave in June of 2009 in North China and HuangHuai, the extreme intensity and westward extension of Subtropical High (SH) in the Western Pacific is the main circulation led to the heat waves in July and August of 2009. South Asia High (SAH) and the Subtropical High have a good response relationship, with the SAH is stronger (weaker) than normal and shifted eastwards (westwards), the SH is stronger (weaker) than normal and shifted westwards (eastwards), daily maximum temperature distribution of South of the Yangtze River will also increase (narrow) accordingly. Low-level divergence, subtropical westerly jet axis shifted northward, jet center located westerly and so on are conducive to the occurrence and maintenance of high temperature in summer of 2009. (3) The abnormality of vertical integrated atmospheric heating filed for whole layer can be used as high temperature maintaining mechanism.