Rain drop size distribution (DSD) contains plenty of information, which reflects not only microphysical characteristics of the rainfall, but also macro-physical properties like rainfall type, rainfall intensity and so on, and has important applications in radar meteorology. In this study, 32 rainfall events data collected by a Parsivel laser spectrometer at Nanjing from 2015 to 2016 are pre-processed and detailed statistics and analysis are conducted. The Gamma-distribution functions of DSD have been fitted for stratiform, convective and mixed-phase rainfall. The Z-R relationships have been established based on the dataset. Polarimetric variables like differential reflectivity Z_DR, specific differential phase K_DP and attenuation parameters are calculated, and the attenuation correction of C-band radar reflectivity factor is tested and validated. The results are as follows. (1) Microphysical variables are less fluctuating for stratiform rainfall, but they vary significantly for cumulonimbus rainfall. Middle-size raindrops contribute more to radar reflectivity and rain rate for stratiform and mixed-phase rainfall, while big-size raindrops make more contributions for cumulonimbus rainfall. (2) The DSD spectral width is the broadest for cumulonimbus rainfall and the narrowest for stratiform rainfall. (3) The accuracy of rainfall estimate from radar measurements can be effectively improved using the fitted Z-R relationship compared to that using the default Z-R relationship. (4) Effective attenuation correction of C-band radar reflectivity factor based on the fitted parameters implies that the DSD statistics and fitting parameters are reliable.