Based on the study of VWP product reliability and its capability representing at mospheric humidity, the characteristics of VWP product in spring large scale rai nfall process in Nanjing are statistically analyzed and studied in detail by usi ng Doppler weather radar data of Nanjing. The results show that VWP product pres ents respective characteristics at different stages of rainfall development (for mation, development and dissipation). The main points are as follows: ND area in VWP images presents a wedge shape and is decreasing quickly, which indicates th e appearance of rainfall within 2 hours; the existence of warm advection, shear layer and strong wind area are propitious to the continuance and reinforcement o f the precipitation; an abrupt reduceof the highest vane in the VWP production or the emergence of ND area in the mi ddle layer predicts that the rainfall will end soon.