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By using the ground and upperair observational data, Doppler radar data, FY2E satellite observational data and ERAInterim reanalysis data, the environmental conditions, mesoscale convective systems, the characteristics of Doppler radar reflectivity, the dynamiclifted condition, and forecasting hints are analyzed and compared between two warmsector heavy rain processes occurred on 17 Aug 2012 and 16 July 2017 in the Western Sichuan basin. The results show: (1) Both processes happened under the background of lowlevel warmmoist flows and ground thermal lows; the “12.08” heavy rain occurred on the edge of the subtropical high pressure system; the moisture transport condition was better; and the heavy rainfall maintained longer. The “17.07” heavy rain happened behind the upper vortexshear, the upper cold advection was more obvious, convective unstable energy was more abundant, and the convective system developed stronger. (2) The mesoscale convective system moved slowly on the edge of the subtropicalhigh pressure and had obvious traineffect during the “12.08” heavy rain; the centroid height of the strong echoes was lower, so it was a kind of mixed precipitation dominated by cumulus clouds, but the mesoscale convective system moved quickly in the highlevel north winds during the “17.07” heavy rain, and the centroid height of the strong echoes was higher, so it belongs to cumulus precipitation. (3) There was a good correlation between the heavy precipitation and the mesoscale convergence line: the ground convergence line provided the enough dynamically lifted condition for the heavy precipitation; both heavy precipitation events happened along with the generation of the convergence line and moved around the convergence line.