According to the micromechanics of composites, the effective elastic respond of Ni-base superalloy was predicted and the parameters of effective elastic propeties of GH4169 as well as its constituent materials i.e. effective elastic modulus E ?, effective bulk modulus K ?, effective shear modulus G ? and Possion’s ratio ν ?, were also theoretically calculated on the bases of macroscopic stress-strain relationship. The results, compared with the theoretically calculation and the experimental measurement in article, are shown that the error of effective elastic property parameters of GH4169 is 7.16%、10.69%、6.58%、0.67%, respectively ; the error 1.42%、0.40%、2.00%、1.66% for γ" phase, which proves the accuracy of the theory. Furthermore, the mesomechanical elastic respond of Ni-base superalloy was predictd in theory and the diffraction elastic constants of γ-(Ni-Cr-Fe) phase of GH4169 alloy, E_220=233.89GPa, ν_220=0.284 were also calculated theoretically, based on mesomechanical stress-strain relationship of Ni-base superalloy under uniaxial loading. Simultaneously, the diffraction elastic constants of the (220) crystal plane of γ-(Ni-Cr-Fe) phase were experimentally measured with the combination of four-point bending to calibrate the load stress and X-ray diffraction for diffraction strain measurement. Contrasted between the theoretical and experimental, the results are demonstrated that the experimental E_220=248.00GPa, ν_220=0.276 and that difference between the theoretical calculation is 5.69%, 2.90% respectively, which proves the accuracy of the theoretical model and also provides a theoretical basis for the study of residual stress measurement by diffraction method as well.