Abstract: Using conventional meteorological observation data, the products of Doppler weather radar and the 0.25° x0.25 ERA5 reanalysis data, this study analyzes a local short-time heavy rainfall in Nanhai District, Foshan City, Guangdong Province from 17: 00 BT to 19: 00 B'T on 1 August 2021. The results show that the circulation background of the short-time rainstorm is a forward trough with an 850 hPa shear line. The strong mid-level upward motions and the persistent low-level water vapoi transport provide favorable dyamic and water vapor conditions for this extremely heavy rainfal. The long-duration existence of the cyclonic vortexes and convergence on the ground may be one of the important reasons leading to the occurrence of this extremely heavy rainfall. This paper also analyzes the meteorological service for the extremely heavy rainfall and summarizes the work experiences, which can provide reference for meteorological seryices in the future.