Using the S-band Dual-polarization radar data and hourly rain gauge data in 2017, the microphysical characteristics of extreme precipitation (more than 50 mm·h^-1) in Guangzhou are statistically analyzed. A comparative analysis of extreme precipitation and strong precipitation (20-50 mm·h^-1) is also applied. The results show that there is little difference between the two types of precipitation with respect of 20 dBZ and 30 dBZ echo height, indicating the intensity of precipitation over Guangzhou has little relation with the height of convection. In the lower layer, stronger average echo and larger raindrops can be seen in the extreme precipitation rather than strong precipitation. Combined with the distribution of Z_H-Z_DR, it shows that both types of precipitation over Guangzhou possess characteristics of maritime convection. Compared with strong precipitation, the values of Z_H, Z_DR and K_DP of extreme precipitation below 0℃ layer are significantly larger, especially at 4-5 km, and they all increase rapidly and continue to increase in the falling process at 4-5 km, indicating that the microphysical processes at 4-5 km are critical to extreme precipitation and thus causing the occurrence of extreme precipitation in Guangzhou.