Since the beginning of the 21st century, frequent extreme weather events have occurred under a background of global climate change. This pattern reflects the characteristics of climate change and drought and floods are one of the most serious disaster impacts for human beings. Exploring the relationship between climate change and drought/flood disasters using climate change performance characteristics has become a prime research problem. Drought/flood events frequently taken place in Yunnan Province, however, few studies have examined drought and flood assessment in this area. Here, the standardized precipitation index (SPI) was adopted to describe drought and flood conditions at five time scales based on precipitation data from 29 meteorological stations in Yunnan. Drought and flood indices during the last 55 years (1958-2012) in Yunnan were estimated,then annual and seasonal changes in station number for drought/flood frequency and drought/flood intensity were analyzed. The results show that drought events increased at multiple time scales. Drought intensity and its influence increased in spring, autumn and winter, while a slight downward trend exists in summer. Flood intensity and its influence generally showed a downward trend. Flood intensity and its influence in summer exhibited a slight upward trend, while other seasons showed a downward trend. Under global climate change the risk of extreme climate events is increasing, which is harmful for agricultural production in Yunnan. The standardized precipitation index has the ability to describe interannual and seasonal variability of droughts/floods over a long period across the region.