Abstract: In order to study the feature of severe convective weather caused by squall line and extract available indicators of this kind of weather for future forecast, using dense meteorological observational data, a thunderstorm gale and hail weather process caused by squall line in south-central Shanxi province is analyzed. The result show that the squall line process occurs at an unstable atmospheric environment caused by the combination of upper cold vortex and surface inverted trough. The occurrence and development of squall line is closely related to the surface mesoscale convergence line. Severe convective weather area is accompanied by surface mesoscale convergence lines or centers. The typical characteristics of squall line weather appeared in severe convective weather stations, which show that pressure soar, temperature drop and wind speed surge. The vertical structure of severe convective area is characterized by upper cold advection superimposed on the low-level warm advection and strong vertical wind shear. The humidity stratification show that the wet low layer is matched with dry high layer and the low wet layer is very thin. This type of stratification determines that thunderstorm gale and hail is the main weather in this squall line process. Also, there is obvious squall line bow echo in radar mosaic.