Abstract: After the syntheses of results which are the structure of hailstorm obtained from field observation and effects of explosion on the breakup of drops, this paper suggested that the explosion may cause the breakup of drops which is melted hail-embryo in embryo curtain located in overhang echo below the 0℃ level, this break effect makes the growth-travel trajectory of hailst one change, there by avoid the formation of large hailst one. The numerical experiments tested and verified this suggestion.