Based on the climate data of sunshine duration, precipitation, average temperature, and so on from 15 representative meteorological stations in Yunnan Province from 1961 to 2010, the natural dry wet climate change and its regional differences in different seasons are analyzed. The results show that the relative moisture index can quantitatively and accurately express the natural climate wet dry status, and objectively reflect the variation over the years and the regional differences for dry wet climate in Yunnan. In the respect of variation trends, potential evapotranspiration was increasing and precipitation was decreasing during both dry and wet seasons since the mid 1990s, which led to obvious aridification trend jointly in Yunnan under the background of climate warming. Meanwhile, the relative moisture index of Yunnan had the bigger inter annual fluctuations in dry season (compared to rainy season) and obvious inter decadal differences. The wet dry climate status of rainy season showed evident periodic variation trends in all regions. Flood drought climate changes of five regions in Yunnan had both consistencies and differences. Especially, the central Yunnan was obviously consistent with the southwestern part, while the northwest was distinctly different from the southeast. The northeast had distinction during rainy season but claimed similarity in dry season with northwest Yunnan.