Abstract: A two-dimensional cloud model including detail microphysics is presented. The precipitation processes of stratiform clouds with or without small-mesoscale disturbances (such as generated cells and natural seeding etc.) and artificial seeding are simulated. The results are compared with observations calulations indicate that in the undisturbant stratiform clouds there exists plentiful supercooled liquid water can not transform to snowfall due to lack of sufficient ice crystals, but when the disturgbances act on the stratiform clouds, there will be a great deal of precipitation. Artificial seeding in the stratiform clouds or the disturbant regions of generated cells can increase snowfall in a large amounts. Mechanisms of the precipitation and artificial enhancement is discussed