A numerical simulation method for anisotropy of 3D printed concrete (3DPC) based on interface model was proposed by applying micromechanics theory of composite materials. This method quantitatively revealed the mechanical behavior of layer/filament interface and its influence on anisotropic elastic constants of 3DPC. By combining interface elements and continuum elements,the interface sliding-cracking behavior and mechanical properties of printed filament were simulated. Uniaxial compression,splitting tension,cross-bonded tension,and inclined shear tests were designed to determine the parameters and corresponding ranges required for model. The research shows that the interface tensile and shear traction-separation curves exhibit a bilinear characteristic,and the strength of filament interface is generally higher than that of layer interface. There is no significant difference in shear behavior in two shear principal directions. The elastic modulus between filament and layer has a linear impact on overall elastic modulus and has an exponential impact on Poisson’s ratio. The shear modulus between filament and layer has a comprehensive impact on overall shear modulus.