Abstract: To better understand the differences in microphysical characteristics of heavy rainfall events in Guangxi, this study utilized conventional meteorological observations, disdrometers, Doppler radar data, and ERA5 reanalysis to examine two heavy rainfall cases: a short-duration intense rainfall event in Guilin on May 22, 2023, and a long-lasting rainfall event in Beihai on June 8, 2023. While the synoptic backgrounds and radar echo features of both events were compared, particular emphasis was placed on analyzing the differences in their ground-based raindrop size distribution (DSD) characteristics. The results are as follows. (1) The short-duration heavy rainfall in Guilin resulted from the interaction of a low-level vortex, a shear line, and cold air intrusion.Convection was strong and well-developed, characterized by a fully developed cold cloud process, with solid particles (including large hail) inferred to exist within the clouds. In contrast, the prolonged heavy rainfall in Beihai was primarily associated with a tropical low-pressure system. Convection was relatively weaker, with strong echo centers located below the 0 °C layer, indicating dominance by warm cloud precipitation. (2) The DSD of convective precipitatio in Guilin exhibited larger mass-weighted mean diameter (D_m) and a lower generalized intercept parameter (N_w), characteristic of continental convective precipitation. By comparison, the convective precipitation in Beihai showed smaller D_m and higher N_w, typical of oceanic convective cloud precipitation. (3) In Guilin, the melting of solid particles in cold clouds contributed to larger-diameter droplets.Additionally, collision and coalescence processes in warm clouds facilitated the formation of equilibrium DSDs. Nearly 80% of the spectra were transitional, indicated that the collision–fragmentation process significantly altered the raindrop size distribution. In Beihai, solid precipitation particles in cold clouds mainly contributed small-size particle spectra. Although warm clouds allowed sufficient time for collision and coalescence mechanisms, the proportions of equilibrium and transitional spectra were much lower than those in Guilin, suggesting a weaker role of the collision–fragmentation process.