To investigate the effects of porosity and pore water saturation on the elastic modulus of concrete at different scales, a multi-scale prediction model for the elastic modulus of wet concrete considering porosity and pore water saturation was established based on the micromechanical inclusion theory. The influence of porosity and pore water saturation on the elastic modulus at multiple scales was analyzed. The results show that the predicted results from the proposed model are in good agreement with multiple sets of experimental results, and the model can accurately predict the elastic modulus of concrete across various scales. The elastic modulus of concrete at the cement paste, mortar, and concrete scales decreases with increasing porosity, and the influence of porosity on the elastic modulus of materials is more pronounced in the dry state than in the saturated state. The elastic modulus of concrete at the cement paste, mortar, and concrete scales increases with increasing pore water saturation, and the higher the porosity, the more significant the increase in elastic modulus with increasing saturation.