The temporal and spatial distribution characteristics of 79 hail processes causing major disasters in 2012-2021 are statistically analyzed by using hail data, radiosonde observation data, ground observation data and EC thin grid data, the characteristics and thresholds of key environmental parameters of hails in different regions, sizes and months are summarized. The results show that: (1) Hails in Shandong have obvious spatial and temporal distribution characteristics, and mainly appear in central and north Shandong. The number of hail days varies greatly from year to year, with a maximum of 14 days and a minimum of 5 days. Hails mainly occur in late spring and early summer, accounting for 65% of hail days in the year and 65% of hail days in the year. Hails frequently occur from 14:00 to 20:00, accounting for 63.3% of the total hail. (2) The average annual occurrence frequency of large hails is the most in central Shandong Province, but the probability of large hails is greater in the peninsula region. Large hails mainly appear in May and June, accounting for 68.6% of the annual number of large hail days. (3) Hails in Shandong have large convective effective potential energy, deep (0 to 6 km) vertical wind shear with medium or above intensity, significant conditional unstable stratification and suitable characteristic layer height/thickness. (4) Different regions, different sizes and key months have certain differences in the characteristics of physical parameters and potential prediction thresholds. Compared with hail falling in coastal areas and in inland areas, hail falling in June and May, large and small hails, it is mainly reflected in the obvious larger convective effective potential energy, smaller dry and warm cap index, greater deep vertical shear, slightly higher lifting condensation height, and thinner thickness of -20 ℃ to 0 ℃ layer.