Abstract: Using the NCEP/CFSR 0.5°×0.5° reanalysis data, FY-2G satellite TBB data, Radar and TREC wind data, etc. in Southern China, the mesoscale convective systems (MCS) characteristics of torrential rain in Xinyi of Guangdong province on 20 May 2016 was analyzed. The results are shown as follows. (1) The heavy precipitation in the heavy rainstorm in Xinyi has lasted for nearly 8 hours, with an average rainfall of more than 50 mm per hour. The heaviest 1 h rain has appeared at 12 noon, reaching 132.8 mm. (2) Factors such as the atmospheric circulation environment of a strong stable 250 hPa divergence system, the slow-moving 500 hPa westerly trough and 925 hPa vortex, and the strengthening low-level jet are the reason why the strong precipitation has been maintained. Strong vertical updraft, favorable atmospheric instability and water vapor convergence conditions are the causes of extreme strong precipitation. (3) The torrential rain event is mainly caused by the continuous effects of the mesoscale convective clouds with TBB≤-52 ℃ and the convective activity center with TBB≤-72 ℃ in Xinyi. (4) The torrential rain has experienced two stages: the first one is generated at the intersection of two echo bands, and then it is produced on the east-west echo. The strong precipitation echoes passing through continuously for a long time, whose train effect is the main cause of torrential rain. (5) Stronger than 40 dBz echoes are all below the -10 ℃ level height, or even below 0 ℃ level height; the strongest echo center is near 2 km height. This kind of low-mass center convective precipitation system has higher precipitation efficiency to enhance the heavy rain. Echo top height was about 19 km; a deep ice growth zone was existed above -10 ℃ level height. These are conducive to the formation of a large number of ice crystals or graupels and ice riming into large ice crystals. When reaching surface, these large raindrops result in instantaneous intensity rainstorm. (6) TREC wind showed that torrential rain occurred in the topography with left side of the ultra-low-level jet on the mesoscale convergence line or near the vortex center.