Abstract: The cause analysis of a wide range hail event occurred in Jiangxi on 19 March 2013 was performed with various data including conventional observation data, satellite images, Doppler-Radar data, observations from automatic weather stations, reanalysis data from NCEP, etc. The results indicate that the hail event occurs under favorable environmental conditions: strong thermal and dynamic instability in middle and lower troposphere provides instability mechanism for formation and growth of hail; southerly jet in warm and moist boundary layer,southwest jet in the low-level and "dry" southwest jet in the medium level have an important contribution to the development of the thermal and dynamic instability mechanism; suitable heights of 0 ℃ level and -20 ℃ level are favorable to growth of hail. The hail event occurring in the northern part of Jiangxi province under the condition of frontal inversion in boundary layer acts as“elevated thunderstorm type”convective weather. The hail event occurring in the southern part of Jiangxi province under the condition of stronger warm advection in boundary layer acts as“non-elevated thunderstorm type”convective weather. The distributions of temperature stratifications in boundary layer for the two types of convection show significant difference. Comparing with the same type of historical cases, vertical change of θse could characterize the development of conditional instability, and also, it has a certain reference for judgment of different types of severe convective weather.