Based on the characteristics of multi-polar and multi-scattering for ice-cloud, the appropriate sub-millimeter atmospheric radiative transfer model is used to analyze the absorption and scattering of atmosphere from 100 GHz-1 000 GHz. The relationship between the sensitivity/calibration accuracy and channel specifications of sub-millimeter ice-cloud imager is analyzed, such as frequency, bandwidth, dual-band and polarization type settings, and then a 15-channel ice cloud imager which covers the frequencies from 118 GHz-900 GHz is proposed. The limitations of the parameter retrievals’ accuracy of ice-clouds distributed in different regions and at different heights in the troposphere are considered, because different geographic locations and altitudes can result in a significantly difference for total ice, ice particle size, shape and direction of ice-clouds. Finally, the specific indicators which will play a vital part in designing the sub-millimeter ice-imager onboard Chinese satellite are proposed.