Abstract: Based on the conventional meteorological data and Doppler radar products,a large hail weather process under the influence of North China cold vortex is analyzed. The results show that：（1） the influence system of this hailstorm is the potential unstable stratification formed by the shallow North China cold vortex,northwest airflow and cold temperature trough at 500 hPa,warm temperature ridge at 700 hPa and 850 hPa;Binhai New Area is located in the divergence zone to the left of the 200 hPa high-altitude jet stream exit zone. It is warm and wet in the lower layer and dry and cold in the middle layer,which is conducive to the occurrence and development of severe convective weather. （2） The effective potential energy of convection is 1 626 J/kg,the convective inhibition is 0 J/kg,the moderate intensity of 0-6 km vertical wind shear is 12.8 m/s,the moderate intensity of 0-2 km vertical wind shear is 10.2 m/s,the humidity below 850 hPa is high,and the humidity above is low,which is favorable for the occurrence of hail and thunderstorm gale weather. The height of 0 ℃ layer is 4.2 km,it is suitable for hail formed. （3） About 1 hour before hailstorm in Binhai New Area,radar products show hailstorm characteristics：reflectivity factor value more than 55 dBz,vertical accumulated liquid water content more than 65 g/kg,and side lobe echo appears,indicating that large hail would fall,and the approaching warning of large hail could be issued about one hour in advance. （4） The strong radar reflectivity factor moves along the direction of 500 hPa guiding airflow and ground convergence line,and is strengthened after entering the Bohai Sea. The mesocyclones are identified by radar and develop into supercell hail storms. （5） The reasons for the strengthening of the hailstorm cells as a supercell storm after entering the Bohai Sea are as follows：the humidity in the lower layer increase,the instability of the upper cold and lower warm potential increase,the vertical wind shear in the deep layer is strengthened,and the divergence field is closer to the left side of the exit area of the 200 hPa upper-level jet stream,which is more conducive to the upward movement and the organization of the storm.

Key words: North China cold vortex, large hail, supercell hail storm