Abstract: Microphysical characteristics and convective structures of heavy precipitation during “24·7” extreme rainstorm event in Henan Province are analyzed using disdrometers, dual-polarization radars, and conventional observations. This extreme rainstorm is successively influenced by the northwestern Pacific subtropical high, a mid-latitude westerly trough and a sliding trough. Resulting extensive regions of heavy precipitation provide favorable environmental conditions for the development of complex and variable microphysical characteristics. Heavy precipitation samples with precipitation intensity exceeding 20 mm·h^-1 are classified into 4 distinct types using Gaussian Mixture Model (GMM) clustering algorithm. The type with an average precipitation intensity over 100 mm·h^-1 is characterized by a larger mass-weighted mean diameter (D_m) and a higher normalized intercept parameter (N_w). In addition, the variation trends of D_m and lgN_w with increasing precipitation intensity are relatively complex. Notably, the precipitation of this type is primarily contributed by large raindrops, with their contribution rate being approximately twice that of medium raindrops. The convective system corresponding to this type is classified as moderate-intensity convection. Active ice-phase processes and highly efficient warm-rain processes within the system jointly lead to high concentrations and large mean particle sizes in the surface precipitation. On the contrary, the precipitation type with precipitation intensity below 50 mm·h^-1 shows characteristics of raindrop size distribution similar to maritime convective precipitation, where the increase of lgN_w contributes more significantly to precipitation intensification, and the precipitation is predominantly contributed by small raindrops. This type is associated with weak convective systems, characterized by relatively low convective cloud-top height, comparatively weaker ice-phase processes, and a dominance of warm-rain processes. Consequently, the surface precipitation is marked by small mean raindrop size and low concentrations of large raindrops. Across all precipitation types, the coalescence process within the warm rain area is identified as the primary warm-rain mechanism responsible for generating heavy precipitation in the event. Comparisons of heavy precipitation across different synoptic stages demonstrate that under the dominant influence of the northwestern Pacific subtropical high, convective development is constrained to lower altitudes, resulting in smaller mean raindrop size. In contrast, during the stage influenced by the sliding trough, convection develops more deeply, and ice-phase processes are more active, leading to larger mean raindrop size. During the stage dominated by westerly trough, convection develops to relatively high altitudes with medium mean raindrop size.