To process the data from 94/220 GHz dual-band radar, the single scattering and attenuation characteristics of ice crystals with different shapes by the two bands were analyzed. The echo characteristics of ice clouds based on single shape ice crystals or a refined model were discussed. The backscatter and attenuation of the larger particles are sensitive to the particle shape. They are the largest for hexagonal ice crystals, greater for bullet, and the least for snow. The radar reflectivity factor (Ze) of ice clouds based on single shape ice crystals are sensitive to the shapes of ice crystals, ice water content and the median dimension of particles size distribution (PSD). The attenuation coefficient of 220 GHz wave is about 5-25 times than that of 94 GHz at the same PSD. Ze of the refined model increases with the particle concentration, ice water content, and median dimension. It is less sensitive to the shape parameters of the PSD.