Abstract: The temporal and spatial characteristics of the different clouds and the relation to precipitation over Northwest China are analyzed using the ISCCP (International Satellite Cloud Climatology Project) monthly mean D2 data from July 1983 to September 2001. Northwestern China is divided into three climatic regions for the purpose of this study. The results show that the plateau climatic region is the one with highest cumuliform cloud amount with low values of liquid water path. The higher cloud amount value areas for most types, especially for high cloud, are over Tianshan Mountains, Kunlun Mountains, Qilian Mountains, and southern Shaanxi and/or southern Gansu, while the lower values of cloud amounts are located over Tarim Basin, the western desert of Inner Mongolia and the northwestern part of Loess Plateau. Also, cloud amount levels are consistent with levels of precipitation. In general, cloud amounts are higher in spring and summer while lower in autumn and winter. The amounts of stratiform clouds associated with higher liquid water path are consistent with precipitation. The amounts of cumuliform and stratocumuliform clouds, however, do not have definite relation to precipitation。