Temporal variation, spatial distribution and sub-regional evolution characteristic of drought on southwestern China and their response characteristic to global climate warming were studied, used drought index analytical method which was based on relative moisture index, according to meteorological data between 1958 and 2012. It provide the scientific basis for coping climate change. Inverse distance weighting (IDW) method of ArcGIS system was used for analytical drawing of spatial data interpolation. The results showed that, annual drought of southwest China mainly distributed in northern Yunnan plateau, western Sichuan plateau and mountainous region of southwestern Sichuan. Drought region covered around 30% of the total region; among which, moderate drought region located in partly of the northern of Yunnan plateau and the western Sichuan plateau, covered around 11% of the total studied region; severe drought region located in northern Yunnan plateau and local area of western Sichuan plateau, covered around 5%; the drought share of 31.7% over the years on the station average. The main drought are winter and spring drought in the studying region, in which the average emergence of winter drought reached76.1% and spring drought reached 46.2% respectially. From 1958 to 2012, the negative absolute value of the relative moisture index increase in middle of Sichuan basin and mostly of Yunnan-Guizhou plateau, indicating the increase of drought level as well as drought intensity. Among which, the Negative absolute value of relative moisture had an increase tendency in most regions of the Yunnan-Guizhou plateau in Summer, autumn and winter, drought significantly enhanced; drought also increase in western Sichuan plateau and mountainous area of southwestern Sichuan in winter; Sichuan basin and north of Sichuan had an increase tendency of drought in autumn; the eastern part of Sichuan basin and Guizhou plateau also had an increase tendency in spring. The time series of index of annual drought has an obvious periodical oscillation of 3~4 a and 7~8 a; 2009 is a mutation year of drought obviously strengthened. It is expected that the drought area will still expanding and the drought intensity will enhancing in the next few years in southwest China under the background global climate warming.