In order to study the scattering properties of non-spherical ice particles which are detected by millimeter-wave radar, the backscattering cross sections of six kinds of non-spherical ice crystals of cirrus were studied. The double-exponential function relationships between particles’ maximum sizes and backscattering cross sections is fitted. Three assumed models: I. B-H mixing model, II. Equivalent ellipsoid model, III. Equivalent sphere model, respectively, were used to simulate the data provided by the NASA’s synchronous satellite and airplanes experiment for cloud observation on July 31, 2007. The results showed that the data retrieved by B-H mixing model agree very well with the measured results at four positions compared with the results retrieved by other two models. However the retrieved results by B-H mixing model at 1#, 2#, 3# positions are lower than values detected by CRS millimeter wave radar. This is because cloud size distribution detector ignores the droxtals which are beyond the detection range. Considering these droxtals and fitting all size distributions at 1#, 2#, 3# and 4#, the common size distribution which meets B-H model can be acquired and the relationship between Ice Water Content (IWC) and Z can be fitted. Putting IWC measured by CVI instrument into above formula (IWC-Z), the retrieved radar reflectivity factors can be acquired, and then compared with the results detected by CRS millimeter wave radar. The results show that the influence of air content on radar reflectivity factor is larger than particle’s orientation when IWC is below 0.134 2 g/m3. The influence of air content can be ignored while the particle’s orientation should be considered when the value of IWC is between 0.134 2 g/m3 and 0.199 4 g/m3. B-H model is not applicable when IWC is larger than 0.199 4 g/m3. Based on above analysis, the orientation and air content must be considered under the premise of IWC in order to accurately retrieve ice particles using millimeter-wave radar.