The major points on dynamical interpretation of NWP products are to put the observed 6-hour rainfall(≥10mm)into the formula calculating the intensity of precipitation and vertical velocity , and then the vertical velocity and the intensity of precipitation forecast given by the model are modified by the model products,u,v,Q and w,finally the rainfall is calculated,The heavy rain forecast in two ways,on grids(1°×1°) and at 435 stations.The verification shows that heavy rain forecasts by dynamical interpretation of NWP products are more or less better than that of the model forecasts for the category, 100mm rainfall. For the categories,25mm and 50mm rainfall,it is worse in August and better in September this year than that of the model forecasts.