Abstract: Based on the conventional observation data, Doppler radar data, intensive network of automatic weather station and NCEP reanalysis data, the characteristics of two local short-time rainstorm processes on July 20^th, 2017 and July 20^th, 2019 in Kunming main city zone were analyzed. The results show that, the two processes occurred under the conditions of two high convergence zones and low-level shears. Unstable stratification, abundant water vapor and surface meso-scale convergence line provided thermal instability, dynamic lifting and water vapor condition for short-term rainstorm. The water vapor condition and vertical ascending motion in the process of "July 20^th, 2019" were more obvious than those of "July 20^th, 2017", so the intensity and range of short-term rainstorm for the "July 20^th, 2019" process were more obvious. Radar data showed that the "July 20^th, 2017" process was dominated by mixed precipitation of stratified-cumulus clouds, and the development of strong echo was relatively higher, while the "July 20^th, 2019" process was dominated by stratified clouds precipitation, which was a low-mass center precipitation structure. In the two processes, the convective echo over Kunming main city zone was continuously strengthening and developing, while moving slowly, and had an obvious small scale convergence area, which played an important role in maintaining and strengthening the heavy rainfall. The surface mesoscale convergence line could predict the occurrence of heavy rainfall for 1−2 hours, and the special trumpet-shape topography has precipitation enhancement effect in Kunming main city zone.