To improve the quality of quantitative precipitation estimation (QPE), the characteristics of local precipitation are analyzed using the measured raindrop size distribution (DSD) data of Nanjing Area in two consecutive summers. The precipitation estimators (PEs) including the relationship of microwave rainfall attenuation and rain rate and the relationship of weather radar intensity and rain rate are calculated based on the DSD data. The relationships obtained are different from ITU-R rain attenuation relationships and commonly used Z-R relationships. The radar Z-R relationship for convective precipitation is Z=161.63R1.55 and Z=227.23R1.53 for stratiform precipitation. Using these PEs, the rain rate distributions in two rainfall cases of different types are retrieved with a microwave link and a weather radar. The results are as follows. The rainfall is overestimated in stratiform precipitation and underestimated in convective precipitation when using ITU-R rain attenuation relationship. The rain rates are obviously underestimated when using commonly used Z-R relationship. The rain rates retrieved with the rain attenuation relationship and the Z-R relationships obtained from the DSD data are more consistent with the rain rates measured by the rain gauges. The mean absolute errors are reduced, and the correlations are significantly improved. The results show that the accuracy of QPE can be improved effectively by using the local PEs calculated by the DSD data.