In 12-15 July 2002,the eastern of Liaoning Province was hit by cold vortex precipitation and hails.In order to analyze the cloud microphysical processes,we used a three-dimensional convective cloud model developed by IAP to simulate this event.According to simulations,the cloud system which produced the precipitation was the convective-stratiform mixed clouds.The mechanisms of ice particles melting played a main role in cloud and precipitation formation,especially graupels melting accounted for about 50% of total rainwater production.Through a series of the modeling calculations of AgI-seeding,we found that the optimal time of AgI-seeding cloud was at the cloud mature stage and the seeding height should be above the 0℃layer.Simulations also show that the convective-stratiform mixed clouds have a considerably seeding potential to enhance precipitation.