Abstract: With the geostationary meteorological satellite, a new Doppler weather radar, ground, WRF numerical simulation and LAPS reanalysis data, we analyze a short-time strong rainfall convective cloud merger case on 30 June 2013 in the mountain area in south of Anhui. Multi-observation shows, this is a merging process of three different occurred successively; the strength of the new convective system from the merger of the two convective clouds is enhancing in a short time.According to the analysis , in the mountain area, summer merger of convective clouds occurred in the environment where the horizontal and vertical wind shear and vertical vorticity are increasing and the wet baroclinic is enhancing instably; the merging process of convective clouds is accompanied with mesoscaleγ system such as cyclone, topographic eddy. strong vertical motion within the cyclone and topographic eddy system leads to low layer convergence,which is the triggering mechanism is a of short-time strong rainfall in mountainous areas.