According to the synoptic background and the evolution characteristics of radar echoes of a strong single hail event occurred in Yongdeng county of Uansu Province on July 8，2003，the jumping change of echo height，intensity and liquid water content，and the special structure features of the strong single hail were analyzed in this paper. 'hhc results show that the range and extension height of strong reflectivity area on vertical section arc important to hailstorm development.  While the strong reflectivity area is corresponding to bunbant  watea area In cloud，and only water content accumulating area being in the cooled 4km,region in the cloud can t0  abundant he benefit to hail development.  <)nec the echo intensity reached 55 dBz and its height was above hail falls immediately. 'hhe strong single hail with special structure developed very strongly.  Above conclusions
arc nificant to hail monitoring and prcwarning.