With the data of wind profile Radar in Tangshan, the stratiform precipitation occurred on 12 February 2009 is analyzed. The results show that windprofiler radar can observe the disturbance of cold or warm shearing and the downward expanding of a jet stream. These small disturbances and downward expanding would enhance and maintain the precipitation. The enhancing of the vertical shear and the strong sinking air indicate the beginning of precipitation. The invasion of northerly winds at lower levels and the disappearance of the strong sinking air indicate the ending of precipitation.