Abstract: Based on ground, high-altitude observations and the FY-2C Satellite Cloud Image data, a severe hail process occurred in Shandong, Jiangsu and Anhui provinces from June 14 to 15,2005 was analyzed. The results show that: (1) The forward trough structure at the deep of the northeast cold vortex was favorable for the formation and maintenance of the unstable stratification, and the southwesterly airflow at the lower level provided water vapor for the occurrence of hail, and the meso-scale convergence line and dew point front on the ground were the main trigger mechanisms. (2) 0~6 km strong vertical wind shear, convective effective potential energy greater than 2000 J·Kg⁻¹, average height of wet bulb at 0 °C was 3.8 km, these favorable conditions provided a suitable environment field for this severe hail. (3) The TBB showed that the center of gravity of the cold cloud cover was lightly eccentric from the west to the east, and the hail area mainly occurred in and near the large cloud top TBB gradient area on the right side of the cloud. (4) The front of the dry air behind the cold vortex interactd with the wet air, triggering new convection and forming the backward propagation. The intensity of the dark area of the cloud map increased and MCS developd. When the intensity of the dark area invaded into the cloud cluster, the MCS split accordingly. When the dark area weakened, the MCS convection weakened.