Aiming at 94 GHz millimeter-wavelength cloud radar, the back scattering and attenuation of non-spherical ice crystals with a variety of shapes are analyzed by DDA algorithm, moreover, the relationship between radar reflectivity factor(Z_e), attenuation coefficient(k) and Ice Water Content(W) is revealed. Results show that:(1) the effects of ice particles types on back scattering and attenuation of ice particles depend on their sizes.(2) In the actual ice clouds, treating the hexagonal or ellipsoidal ice crystals as the same volume spherical particles would underestimate its attenuation and back scattering, however, treating aggregations as the same spherical volume would overestimate the scattering and attenuation. The back scattering of bullet flower crystals, compared with the spherical volume, may decrease or increase, but the attenuation is certain to be smaller than the spherical particles.(3) Ice models have great effects on Z_e-k, Z_e-W relations. The relationships between attenuation coefficient and radar reflectivity factor are derived based on refined models for the ice hydrometeors in the case of same particle size distributions. The results help process Chinese W band cloud radars data.