Abstract: Geotechnical materials are usually distributed horizontally in layers, which can be regarded as transverse isotropic materials. Transverse isotropy has a significant effect on the deformation and strength of geotechnical materials. Based on the proposed t-strength criterion, the t-strength criterion is proposed on the physical concept of the existence of an effective slip plane in the isotropic element body, and the failure condition is fulfilled when the ratio of the principal shear stress to the principal normal stress on the space effective slip plane reaches a certain threshold. Effective slip plane in space and physical deposition surface, based on the position relationship between the two surfaces in the space, the idea is proposed that two surfaces angle as a characterization of transverse isotropy can influence the shear strength parameters, and assume that when the angle of value, the greater the strength of the anisotropy of the contribution degree is, the greater the corresponding stress ratio strength value is, on the contrary, the corresponding smaller stress ratio strength value is. Based on the above ideas, the two surfaces angle is regarded as a parameter to construct anisotropic stress ratio strength formula, and use the stress strength formula for correction, a new anisotropic criterion has been put forward based on t strength criterion, finally transverse isotropic t criterion formula of strength criterion is proposed. On the basis of the above criteria, considering transverse isotropic stress space into isotropic stress space, based on the rule of anisotropic t, transformation equation is derived based on the transverse isotropic strength t criterion. It can be used to convert the traditional p and q as the variables of the isotropic constitutive model into the transverse isotropic three-dimensional constitutive model. By predicting the strength of rock and soil materials and the stress-strain relationship test data under true triaxial condition, the validity and applicability of the proposed transverse isotropic t criterion and its stress transformation formula are verified.