Calculated with a constructed contingency table was entropy function, which was used for assessing five rainstorm forecasts (June 22-August 7, 1996) as T63 and HLAFS model products issued by China National Meteorological Center (NMC), leading to as many numerical products that offered information of 0.182 4～0.291 4 bits for different regions of Jiangsu province in preparing rainfall prediction.