Using the observation data of automatic weather station, MICAPS weather map, Jiangxi two-dimensional and three-dimensional lightning data and Jiangxi WebGIS radar mosaic, the evolution of echo system of Jiangxi strong squall line weather process from May 10 to 11, 2021 is analyzed. The results show that when Jiangxi is located in front of the 500 hPa trough, 100 hPa outflow area, 850 hPa shear line and southwest jet stream, 925 hPa southwest inverted trough, it can be conducive to the occurrence of hail, thunderstorm, gale, strong lightning and other extreme weather. A squall line process has several different multi-scale echo system processes, including mesoscale convective echo system, local geothermal convective thunderstorm echo, thunderstorm echo group.'A squall line’ echo zone, convergence line thunderstorm echo zone,'B squall line’ echo zone and so on; Hail(d≤2 cm) occurs when the echoes with composite reflectivity (CR) echo intensity exceeding 60 dBZ and strong echo area exceeding 100 km² is detected, and large hail (d≥5 cm)is prone to occur, when CR intensity more than 65 dBZ and strong echo area exceeds 300 km².