Abstract: The Duncan-Chang nonlinear model based on the Mohr-Coulomb strength criterion can better reflect the shear strength characteristics of the soil, but it is not suitable to reflect the tensile strength characteristics of the soil. In order to reflect the tensile strength of the structural loess reasonably, firstly, the strength of soil is re-determined by introducing the joint strength criterion into the Duncan-Chang nonlinear constitutive model, and the failure stress ratio based on the joint strength theory of structural loess is corrected. Then, the tangent deformational modulus is re-determined by the modified failure stress ratio. Finally, the tangent Poisson's ratio is modified by the modified tangent deformational modulus, and the Duncan-Chang nonlinear constitutive model based on the joint strength theory is established, which provides a new method for reasonable consideration of the tensile strength characteristics of structural loess in the study on the stability of structural loess slopes.