According to the analyses on the synoptic situation,satellite image,radar echo and AWS data,it is found that there is a vortex selforganization process during a recordbreaking torrential rainfall in Shanghai on 25 August 2008.A surface mesoscale low develops during the heavy rainfall,which has a close connection with the organization and combination of meso and microscale vortices.Growing of the surface low stirs up the intensive precipitation and brings Shanghai city with the recordbreaking heavy rainfall.The process that forecasters applied the vortex selforganization theory on the forecast of the heavy rainfall is also detailed,which promises the theorys broad prospect on operational forecasting.