Based on the raindrop disdrometer data of 42 stations in Shanghai, Zhejiang, Jiangsu and Anhui during the precipitation process of Typhoon Rumbia （1808）, this paper compares and analyzes the difference between the radar reflectivity calculated from raindrop size distribution and the actual measurement based on radar, and the difference between the raindrop size distribution inversion rain rate and gauge actual observation. The ZR relationship fitting is carried out to explore the relationship between radar echo and the precipitation intensity of typhoon. Two kinds of ZR relations are used for comparative analysis of precipitation estimation so as to explore the application effect of raindrop size distribution. The main results are as follows. The radar reflectivity factor of raindrop disdrometers inversion is consistent with radar observation, with correlation coefficient being 0.96, and the former is slightly smaller than the latter. Comparison suggests that the rainfall intensity observed by rain gauge and the precipitation intensity calculated by raindrop disdrometer data have the almost same varying trend, and their correlation coefficient is 0.94. However, the values from some instruments have great differences in some regions, which may be caused by the system error of the instrument itself in the region, and also by the influence of typhoon. When raindrops fall to the ground, the falling speed is fast so that they are easy to break, overlap, etc. This could cause some errors in the diameter and number of drops. In addition, the fitting formula of precipitation echo and intensity of the cloud system around the Typhoon Rumbia is Z=188.85R1.42. The estimation effect by using this relationship is better than using the default relationship Z=300R1.4, increasing by about 17% of precipitation estimation.