Abstract: A stress-induced constitutive model of laminated NiTisingle crystal was constructed. Based on the laminated microstructure ofmartensite twins and the difference of the elastic anisotropic propertiesbetween austenite and martensite phases, we constructed the model usingthermodynamics with perfect interface condition. We also numericallysimulated the evolution of micro-stress and strain during phasetransformation and the response of stress-strain to the different loadingdirections. The numerical results show that NiTi single crystal hashardening or softening mechanical properties during transformation accordingto the different loading directions.