A microcomputer processing system for cloud classification using GMS bis-pectral images (the cloud classification system for short)is designed. In addition to theroutine functions, such as image quantization, sampling, storage, display and local am-plification, it can process monospectral or bispectral satellite images. For monospectralsatellite images, it can be used for 1-dimensional histogram analysis and the contraststretching and pixel frequency statistics in the arbitrary value domain, and for bispectralsatellite images, rectangle classification and spatial coherence are adopted for cloud clas-sification on the 2-dimensional histogram. Thus, the cloud classification system candisplay the cloud images and perform the precipitus classification as well as the pixelnumber and cloudiness percentage of various clouds and precipitus clouds.