Abstract:The following are the main characteristics of the general circulation of atmosphere in May 2011. There are two centers of the Northern Hemisphere polar vortex and four waves around the earth in middle high latitudes. More troughs occur in middle high latitudes in the Asian area, and lead to several streams of cold air which influence China. The East Asia major trough is stronger than usual at same time period. The subtropical high and the southern branch trough are near climatological normals. The monthly mean temperature averaged over China is 17.7℃ which is 0.3℃ higher than climatological normals, and the monthly mean precipitation averaged over China is 81.4 mm which is 12.1% less than climatological normals (92.6 mm). There are two cold airs, seven precipitations and one strong sand dust process in May 2011 respectively. Rain storm and flooding occur in Sichuan, Hunan, Guangdong, Guangxi, etc. Meanwhile, the drought continues developing at the middle and lower reaches of the Changjiang River. Strong wind and hail disasters hit Xinjiang, Gansu, Ningxia, Hebei, Shandong, Hunan, Guizhou, Guangdong, etc.