Abstract: In this paper, a review of properties of cirrus is given. The knowledge of composition and structure of cirrus is described. Then, the geometric ray tracing method is proposed, which is first applied in this field by Cai and Liou. C-L method is approximately valid because the ice crystal of cirrus is more larger than wavelength of the researched laser. This computation depends on the optics, which can give the scattering phase matrix of polarized light for the randomly oriented non-spherical particle. As result, the matrix element of scattering of hexagonal ice crystal, the scattering cross sector and absorption cross sector is calculated.