A predicting model, low frequency synoptic chart, is developed to forecast severe precipitation events in Hunan Region based on NCEP/NCAR reanalysis data of 500 hPa height and 700 hPa winds as well as the daily rainfall data from 97 observation stations in Hunan Province during 2006-2010. Meanwhile, the synoptic key regions are determined and the characteristics of low frequency waves are analyzed. Using historic data for validation, the average fitting rate of hindcast is 64.4% in April, 54.9% in May and 50.7% in June. Compared with the lead time of 10 d, 15 d, 20 d and 25 d, the fitting rate of hindcasts increases to the maximum at the lead time of 30 d. Applying the data to the forecasting of the severe precipitation events from April to June 2011 gives a good prediction result with the accuracy rate reaching 70%, the vacancy rate being 30% and no missing rate