Abstract: While a spatial object is observed by a ground detection system, some important influence of cirrus scattering on the target detection and identification might occur. In this paper, a review of single scattering and distribution properties of regular geometric cirrus particle is given. Micro physical properties are analyzed ulteriorly. Based on an assumption that size distribution of cirrus particles is a Gamma function, the phase function with the scattering angle is simulated within wavelength 0.4 mm to 4 mm and effective radius 10 mm to 120 mm. An approximate model of multiple scattering probability concerning ice crystal particles and photons is proposed. Numerical results show that optical depth of cirrus increases with the order of multiple scattering.