The mechanical properties of concrete under the effect of long-term radiation are significantly degraded, affecting the long-term operation of existing nuclear power plants. The state-of-the-art on multi-scale evolution of the volume and mechanical properties of concrete under radiation was reviewed and analyzed. It was indicated that the evolution mechanism of volume and mechanical properties of minerals, aggregates, hardened cement paste, and concrete have been understood, and the multi-scale numerical model to predict the performance degradation of irradiated concrete has been developed. However, it was suggested that the multi-scale model of irradiated concrete based on mineral composition should be developed for reliable prediction of the volume and mechanical property, considering the randomly distributed aggregates at the mesoscale level and the differences in irradiation effects of the components.