Abstract: The spatial-temporal distributive features of the extremely severe drought and the anomalous atmospheric circulation in summer 2006 are analyzed based on the NCEP/NCAR reanalysis data, the circulation characteristic index values given by the National Climate Center, and the daily precipitation data of the 20 stations in the east of southwest China from 1959 to 2006. Results show that the rainless period in summer 2006 started from early second dekad of June and ended in middle and late first dekad of September, totally more than 80 days, and the rainfall was especially scarce from middle third dekad of July to middle first dekad of September. Precipitations for the whole summer or each month were all less than normal level, and precipitation indexes show that the summer precipitation in 2006 was the least one since 1959. The extremely severe drought in the east of southwest China in summer 2006 has close relationship with persistent anomalies of the atmospheric circulation in the same period, i.e. anomalies of mid-high latitude atmospheric circulation, Western Pacific Subtropical High(WPSH), westerlies circulation, south Asia high, lower-level flow, water vapor transport, vertical movement and so on. The extremely severe drought could occur in the east of southwest China when the WPSH lies anomalously to the north and west of normal position or when it is anomalously weak and lies to the east. The cause for the high temperature and extreme drought in summer 2006 belongs to the former. The WPSH became stronger and shifted to the north and west of normal position, and meanwhile the south Asia high was also strong and lay to the east of normal position. The downdraft prevailed over the east area of southwest China under the control of the WPSH, and suppressed the water vapor transfer towards this area. At the same time, the disposition of the westerlies circulation and the midhigh latitude circulation was disadvantageous to the southward invasion of cold air. All those jointly resulted in the extremely severe drought event in the east of southwest China in the summer of 2006. The weak heating over the Tibetan Plateau and the vigorous convection activities over Philippine area are likely responsible for a strong WPSH and it's northwest shift in summer 2006.