Rainfall is the main driving force of soil erosion in the southwest China. It shows that rainfall erosivity has the potential ability causing severe soil loss. So, It is of great significance to soil erosion monitoring, assessment, prediction and control by researching on the temporal and spatial variation of rainfall erosivity in southwest China. Based on the daily rainfall amounts of 129 meteorological stations, the rainfall erosivity was calculated in the southwest China. With the method of trend coefficient, climate tendency rate and kriging interpolation, the rainfall erosivity trends were discussed. The result indicated that the spatial distribution of average annual rainfall erosivity is nearly the same as that of average annual precipitation. There is significant temporal difference of rainfall erosivity in the Qinghai-Tibet Plateau of the northwest of the study area, and the Cv value is higher than 0.40. The rainfall erosivity of most of the study area shows increasing trend during the last 50 years which indicates that the potential ability of the soil loss caused by rainfall increases in southwest China. But, the rainfall erosivity shows decreasing in the area of Chengdu Plain. The coefficients of tendency increase with increasing altitude, and it is particularly evident in areas above an altitude of 2 500 m. The higher altitude enlarges the increasing trend of rainfall erosivity.