A multi-level simulation method is presented for predicting the elastic moduli of hardened cement paste.Based on the geometrical scales of the constituents in cement paste,the structure of the hardened cement paste is broken down into two levels.At the first level C-S-H and CH are involved,whereas at the second level hydrated gel,unhydrated cement and capillary pores are all included.By applying the exact solution for the elastic moduli of two-phase composite materials,the elastic moduli of low-density and high-density gels are obtained.By breaking down the three-phase composite sphere model into two two-phase composite sphere models,the elastic moduli of solid and hardened cement pastes are then computed step by step.The advantage of the proposed method is that the elastic moduli of hardened cement paste are related to the volume fractions and elastic moduli of the constituents in a quantitative manner,which lays a theoretical foundation for optimization design of cement paste.Finally,the validity of the method presented in this paper is preliminarily verified with experimental results reported in the literature.