The optimization approach was applied to the four rainfall events in 2007 to clarify the Z-R power relationship in Beijing region.Daily rainfall data and 6-minute resolution NEXRAD reflectivity data were collected,based on which 122 pairs of daily gauge and radar standard base data were prepared for each rain event.It was found that by using the optimized Z-R relationship the difference between the radar estimated precipitation and the gauge data could be further reduced than by using the default Z-R relati...