The invention discloses a method for improving the fatigue resistance performance of mechanical parts or structural parts, comprising the steps of embedding internal material which is superior to surface material in elasticity modulusin into an appropriate position in surface material with high plasticity and toughness. When some mechanical parts designed in a conventional method are checked and proved to be rich in strength, part of material originally designed in the appropriated positions in the mechanical parts are removed and replaced by material with high elasticity modulusin according to the surplus strength and the strength of the concretely stressed material of high elasticity modulusin, so that the mechanical parts have improved rigidity, are less deformed under the action of alternating stress and are not so easily prone to microfissures and rapid extension of existing microfissures, and the fatigue resistance performance of structural parts or the mechanical parts are improved finally. In addition, because the internal material with higher elasticity modulusin are embedded in the structural parts or the mechanical parts, the rigidity of the structural parts or the mechanical parts is improved, and further the rigidity of the whole system is improved, the occurrence frequency of errors resulted from deformation is reduced, and the transmission accuracy and the work accuracy of a machine are improved.