By using the precipitation data in the dry season from 19(51 to 1994 and the same time synoptic maps, the severe precipitation factors and features of circulation prior to the occurrence of the regional severe precipitation are analysed. Six circulation patterns are classified from numerous cases and the indexes of forcasting severe precipitation are discovered from the every day data. The forecasting indexes of severe precipitation for two circulation patterns are given, which is proved to he practical value in the dry season severe precipitation occurrences in Sanxia on the Changjiang in recent two years.