A WRF-based AgI-seeding model has been developed and used to simulate cloud seeding effects on cloud physics and precipitation of a convective cloud system in Beijing. The effects of diffusion and transport of seeding agent under different seeding locations, seeding time and seeding amounts on cloud hydrometeor and precipitation have been discussed. The results show that the diffusion and transport of AgI agent are strongly dependent on the seeding location. AgI injected into the maximum supercooled cloud water area or the maximum updraft area can be transported to the region of abundant supercooled water. It needs longer time for AgI seeded into the upper and lower inflow areas transporting to the supercooled water area of the cloud, and most of the particles assemble at the edge of the cloud. The seeding induces the rapid depletion of supercooled water and the increase of cloud ice particles. The graupel content translation decreases and the snow formation enhances. The latent heat from the supercooled water freezing enhances the vertical velocity and the rainfall increases because the rain water content increases. The precipitation change is greatly affected by the seeding rate (SR) . When the SR is 0.6 g/s, the seeding can influence surface rainfall for more than 4 hours and has a better effect on precipitation enhancement. When the SR is 0.1 g/s, little rainfall can be enhanced. The rainfall can be suppressed when the SR is 1.2 g/s. In the case of SR being 0.6 g/s, the 12-hour surface precipitation with AgI seeded in the upper inflow area is increased by 48.7% compared with that with AgI seeded in the maximum supercooled cloud water area. The effect in the case seeded in the maximum updraft area is the most. The precipitation is enhanced by 72.1% in the case seeded in the maximum updraft area compared with that seeded in the maximum supercooled cloud water area.