A laser optical disdrometer (HY-P1000) and a two-dimensional video disdrometer (2DVD) were used to measure the raindrop size distribution (DSD) at the Longmen, Xinfeng and Fogang weather stations in Guangdong Province. Differences between the DSD measured by HY-P1000 and 2DVD and the accuracy of precipitation retrieval in the same place and same time were analyzed. The fundamental equations used for quantitative precipitation estimation (QPE) algorithm were fitted by the disdrometer data collected during 2018 and 2019, and then the optimization rainfall algorithm (HCA-QPE) based on the equations above was applied to Guangzhou S-band dual polarization weather radar to improve the accuracy of QPE in Guangdong. The results showed that the 2DVD is more sensitive to small rain drops (<1 mm) while the HY-P1000 can measure much more rain drops larger than 3.5 mm. The polarization parameters retrieved from two types of disdrometers are different from those observed by S-band dual-polarization radar at 0.5° elevation, and the difference of differential reflectivity was relatively large. What’s more, using 2DVD observation data can improve the QPE accuracy of S-band dual polarization radar, especially for light to moderate rainfall.