The effects of three ideal types of terrain on clouds which move with ambient wind have been simulated by using a two-dimensional slab-symmetric warm cloud model. A simple technique of terrain processing is used. And the results of this modeling are fairly consistent with observations.The modeled clouds moving over isolate mountains or into mountain areas undergo some enhancement, with larger amount of rainfall, whereas those moving out of mountain areas become weakened a lot. The effect of terrains is more obvious in the early developing stage of the clouds.The downdraft of the local circulation formed because of the heating of the mountain slope has a slight negative effect on the development of the approaching clouds.