By using surface and 500hPa weather map and precipitation data from 1961 to 1994, the relationship between the one ridge-one trough circulation pattern and regional severe precipitation during the dry season (Oct. —Jan. ) in Sanxia on the Changiang was analysed. The characteristics of temporal and spatial distribution of warm high ridge associated with severe precipitation were analyzed and the day by day checking was carried out,and the forecast indexes of severe precipitation were summarized. The checking was carried out with the application of the weather map and precipitation data in 1995. The results were good . The study have been applied to the informal forecast during Oct. —Jan. in 1996. The trial were quite good and the forecasting indexes possess certain value of reference.