Based on the outputs of the high-resolution regional climate model (RegCM4) driven by the results of five global climate system models, the simulation performance of RegCM4 for precipitation extremes in Southwest China is systematically evaluated. Furthermore, the future precipitation extremes in Southwest China are also evaluated. The results indicate that the RegCM4 models can reasonably reproduce the climate means for the period from 1986 to 2005, but there are greater biases over Southwest China, especially over central Sichuan and the Sichuan basin. Thus, bias correction is implemented on the RegCM4 outputs, and it can significantly reduce the bias of precipitation extremes over Southwest China. For future changes in precipitation extremes, the total wet day precipitation (Prcptot), very heavy precipitation days (R10mm), maximum day precipitation (Rx1day), and extreme precipitation (R95p) are projected to increase significantly across Southwest China over the 21st century under the representative concentration pathways (RCP) 4.5 and 8.5 scenarios. Compared to the current climate (1986—2005), all the precipitation extreme indices exhibit an increasing trend in the future. Both Rx1day and R95p are projected to increase in most areas of Southwest China under the scenarios of RCP4.5 and RCP8.5 in the 21st century, and are reported to respectively increase by approximately 16.0% and 12.6% at the end of the 21st century under the RCP4.5 scenario. The future changes in Prcptot and R10mm show great regionality, with both showing a decreasing trend in southern Yunnan and the Sichuan Basin, while the other regions show an increasing trend. Additionally, these changes in Prcptot and R10mm under the RCP8.5 scenario are considerably higher than those under the RCP4.5 scenario.