Based on first-principles, phase field method, and elastic self-consistent theory, the influence of fission fragments on the Zr elastic modulus was analyzed through the multi-scale simulation. This research revealed the influence of the fission fragment elements and irradiation voids on the Zr elastic modulus. Results show that the fission fragment Xe dissolves in Zr matrix can reduce the elastic modulus, while the effect of irradiation voids on the elastic modulus is relatively small. Meanwhile, the quantitative relationship model was established between the elastic modulus (E) and the changes in irradiation damage dose (D) and temperature (T), . This work lays a technical foundation for the refined analysis of the mechanical properties of Zr alloys after irradiation.