Abstract: The basic principle of MODIS multispect ral cloud phase recognition is introduced, with the algorithm for cloud phase recognition investigated.Radiosonde observations and MODIS tri-channel composite images are used in the paper to show the rationality and the effect of cloud phase recognition in cases.The analysis of large cloud scenes in some special weather background indicates that the technique of multispectral cloud phase retrieval is quite steady to be applied in practice and some visible techniques should be imported to reduce the error which is unavoidable in the analysis of multilayer mask and thin cirrus with inf rared technique.