Abstract: On 21 February 2024, a mesoscale convective system accompanied by hail developed across Jiangxi, Fujian, and Zhejiang. To investigate the evolution of dynamic structure and hydrometeor types of the persistent hailfall-producing cell during different stages, this event is analyzed based on S-band dual-polarization radar data. Results show that the synoptic conditions in the upper and lower levels constitute a typical elevated convective environment. During the mature stage,3 radar parameters, the maximum reflectivity, echo top height and vertically integrated liquid water, show significant increases compared to the development stage. Large hail occurrence corresponds to higher values of maximum reflectivity, echo top height and vertically integrated liquid water. A sharp increase in vertically integrated liquid water content can serve as an indicator for the occurrence of large hail at the surface. Persistent and strong mesoscale convergent updrafts are identified as the primary dynamic mechanism responsible for the continuous hailfall. Z_DR column appears consistently throughout both the development and mature stages, with its height gradually decreasing as the mesoscale convective system hailfall event progresses. During the development stage, Z_DR column extends upward to -5 ℃ level. The updraft within the column rapidly transports raindrops from the warm sector into the cold sector, forming a hail embryo region above Z_DR column. During the maturation stage, Z_DR column persists with the sustained strong updrafts lifting more liquid droplets into the cold sector. This enhances the supply of supercooled water and hail embryos, which continuously form in the wet growth region between -20 ℃ and -10 ℃. Embryos grow into hailstones through the accretion and freezing of supercooled cloud water. When hail begins to descend, the drag effect caused by falling hail particles lowers Z_DR column height to 0 ℃. The vertical configuration of radar polarimetric parameters varies during different stages of the mesoscale convective system and under hailfalls of different intensities. During the development stage, hail particles have already formed in the cold region, characterized by negative Z_DR, low correlation coefficient and negligible K_DP. This period represents favorable timing for artificial hail suppression. In the mature stage, the area extent of hail particles in the cold region expands significantly compared to the development stage, with particle phase becoming more uniform, reflected by an increase in the correlation coefficient. The negative Z_DR zone extends vertically downward, while in the warm region, partial melting of descending hail particles along with raindrops results in a mixed phase region. This mixture leads to a decrease in the correlation coefficient and an expansion of the area characterized by absent K_DP.