Abstract: Abstract: Maize, as a major grain crop in Southwest China, has contributed significantly to total grain production in the region. Drought is the most prominent agro-meteorological disaster which poses serious threat to maize production. Therefore, it is important to analyze its temporal and spatial distribution characteristics and occurring regularities to provide technical supports for disaster prevention and reasonable layout of maize production in Southwest China. In this study, daily meteorological data, collected from 60 stations in maize planting areas of Southwestern China during 1960-2010, were used to calculate the Agricultural Reference Index for Drought (ARID) which computed daily and based on three important factors (soil ,vegetation and atmosphere). The spatial distribution of drought frequency at maize growth periods and annual variations of drought in recent 50 years were analyzed to validate the application of ARID in this region. The results showed there were obviously regional characteristics in recent 50 years. Drought happened most frequently in north center and northeast of YunNan and south of SiChuan，followed by GuanYuan of SiChuan areas, mountains of southwestern SiChuan, northwestern YunNan, YuanJiang and its surrounding areas. Areas with the lowest incidence of drought mainly located in the most regions of ChongQing, the north of GuiZhou and other regions. Drought occurred with the highest frequency at the stage of emergence to jointing and the lowest frequency at the stage of tasseling to filling. In addition, with the development of the growth, drought occurrence had the tendency to move to the east. ARID extremely differed in sub-regions of Southwestern China during maize growing periods. In general, light drought happened in higher frequency than moderate and severe drought. Specifically, only a few regions were moderate drought or fluctuated between light drought and moderate drought. The inter-annual change feature of ARID showed that drought was light in 1980s and became more serious at the beginning of the 21st century.