The hailstorm process in the northwest Guangxi is simulated with 3D convective cloud model. The results show that the model is capable to simulat e the case to some extent. A series of seeding experiments indicate that the cum ulus cloud has some potential to be artificially modified. Effect can be optimiz ed by proper seeding at the base of the supercooled water area as natural crys t al concentration is still at a low level. Seeding may somewhat cause the rainfal l enhancement as well as the hail suppression. Meanwhile over seeding may lead t o the rainfall decrease as well as the hail suppression.