The paper aims to deepen the understanding of warm-sector heavy rains and improve the prediction accuracy of such heavy rain. In this paper, based on the onventional observational data, medium scale hourly precipitation data, and NCEP 1°×1° grid point reanalysis data, the contrastive analysis of two warm-sector rainfalls (May 14th-15th, 2015 and June 13th-14th, 2015) in Guangxi was performed. The results showed that: both of the rainfalls occurred in the southward airflow at 850 hPa; there was unstable energy accumulation before the heavy precipitation; strong vertical wind shear at the lower layer of 925-850 hPa accelerated the development of the onvection system; mesoscale surface convergence line was the trigger mechanism of the unstable energy release. The differences between the two rainfalls were: during the rainstorm in May 14th, subtropical high was enhanced and stretched westward; quasi-stationary appeared in mesoscale convection system; convective clouds greatly grew into a mixed precipitation echo featuring cumuliform cloud; the prefrontal ? type high energy tongue was relatively wide; jet stream in the low altitude was strong and stretched high, which facilitated the water vapor transportation in the lower atmosphere and the development of vertical movement. While in the rainstorm in June 13th, subtropical high weakened and retreated eastward;‘train effect’caused continuous precipitation; the extension height of convective echo was relatively low; the rainfall was a mixed precipitation of sheet cloud and cumuliform cloud; and an environment with high humidity of the whole layer reduced the evaporation, which was favorable for the formation of wide-range precipitation.