Abstract: Freezing rain/heavy snowfall processes occurred in the southern part of China from 10 January to 2 February 2008, which is featured with a broad spatial scale, long duration and strong intensity. The observational ability and attenuation characteristics of a millimeter-wavelength radar are introduced in this article. The cloud profile radar (CPR) data on CLOUDSAT were used to analyse the freezing rain/heavy snowfall processes to explore their cloud physics mechanism in Hunan Province and Guizhou Province. The results show that: (1) the millimeter-wavelength radar could observe the fine horizontal and vertical structures of cloud systems, and distinguish the melting process of cloud; (2) cloud phase transition within the freezing rain/heavy snowfall processes in Hunan during January is along the direction of “snow-rain-supercooled rain”, while in Guizhou during February is along “supercooled cloudsupercooled rain”. Both of the intensity and thickness of zero temperature melting layer as wall as the surface temperature are key factors to the freezing rain to form; and (3) the millimeter-wavelength radar shows a great potential in helping us to study the ice and snow weather. Combining the cloud radar with the other remote sensing techniques will make significant contribution not only to weather mechanism investigations and cloud physics but also to climate change and weather modification.