Comprehensive analyses and researches on synoptic situation,satellite images,radar echo and disasters were carried out for a supercell on May 27,2002，which is the most severe one during last 50 a in north area of Anhui Province.Results show that the interaction of multi-scale synoptic systems results in the small-scale thunderstorm cell transforming into mesoscale convective systems which leads to this supercell storm.Cold advection on upper level overlapping warm advection on low level and the temperature and moisture increasing on low level offered ample energy.The strong concentrated and upward vertical movement overlapping the convective movement region is the dynamic mechanism which stimulated the severe convective storm.This paper reveals the radar echo characteristics of a supercell storm,offers reference on synoptic and radar echo to detect and nowcast severe convective storm.