Abstract: Based on the forming process and the characteristics of frozen soil,it was pointed out that frozen soil could be named as orthotropic material.With the application of mechanics of composite materials and the tests on stress and strain,elastic modulus,Poison’s ratio in three principal planes under different temperatures,frozen soil could be regarded as the nonlinear transversely isotropic material.It could provide the basis for new constitutive model of frozen soil and numerical analysis on interaction between frozen soil and buildings.