A stratiform preicipitation during 20-21 March 2008 is simulated using the mesoscale model MM5V3 coupled with CAMS explicit cloud microphysics scheme. Simulation of rainfall is very similar to observation. Adding artificial ice particles at different area and time can lead to different results. When seeding is maded in areas with high content of supercooled water and low content of ice particles, surface precipitation will be increased. After seeding, supercooled water decreases while ice, snowfall and graupel increases. Above the seeding level, the collection of ice by snow, the conversion of ice to snow are the main source of snow; below the seeding level, the collection of supercooled cloud water to snow is the main source of snow. The collection of snow to supercooled raindrops is the main source of graupel. The main source of raindrops is the collection of raindrops to cloud water.