Taking the Jianghuai Meiyu precipitation event on 19–20 June 2025 as a case study, this paper investigates the microphysical characteristics and latent heat structure of Meiyu precipitation using the three-dimensional observations and retrieved precipitation and latent heat products from the Precipitation Measurement Radar onboard Fengyun-3G (FY-3G), with ERA5 reanalysis data employed for joint verification and mechanism analysis. The results show that Meiyu precipitation is a mixture of stratiform and convective precipitation across different scales, primarily originating from widespread stratiform precipitation, followed by embedded deep convective cloud clusters. The bright band corresponds well with stratiform precipitation. The upward motion above the bright band promotes the melting and collision–coalescence of ice particles, forming a cloud water accumulation zone that produces persistent stratiform precipitation. Convective precipitation echoes mainly originate from low-level cloud systems and are accompanied by strong vertical motion. In stratiform precipitation, the scatter distributions of particle diameter and concentration are relatively concentrated, both showing a decreasing trend with increasing height. In convective precipitation, the particle concentration and diameter exhibit pronounced discrete distributions, scattering toward larger diameters and higher concentrations at low altitudes and toward smaller diameters and lower concentrations at high altitudes. During stratiform precipitation, the particle concentration ranges in the warm and cold regions are similar, but some particle diameters in the warm region are noticeably larger than those in the cold region. During convective precipitation, compared with the cold region, the particle diameter and concentration scatter in the warm region exhibits a discrete pattern toward smaller diameters and higher concentrations. The latent heat data indicate that the greatest latent heat release occurs near the melting layer, with the greatest latent heat absorption in the lower atmosphere, and a pronounced latent heat absorption zone exists within 1 km below the melting layer. The ERA5 data confirm the reasonableness of the FY-3G latent heat data, with a correlation coefficient of 0.64 and a root-mean-square error of 2.0 K·hr?1. The statistical consistency in vertical distribution between the ERA5 apparent heat source Q1 and the FY-3G latent heat verifies the physical mechanism of latent heat release through water vapor phase transitions in the melting layer. The results of this paper provide key observational evidence for understanding the fine-scale structural characteristics of Meiyu, and the revealed vertical differences in stratiform/convective precipitation particle spectra and the vertical structure characteristics of latent heat can provide observational constraints for the parameter settings of relevant processes in microphysical parameterization schemes.