First principles simulations based on density functional theory have been performed to investigate the electronic structure properties of αL-dicalcium silicate(αL-C2S),β-dicalcium silicate(β-C2S)and γ-dicalcium silicate(γ-C2S).The aim is to elucidate the effect of the crystal structures on reactive sites and further reveal the relationship between polymorphs and hydration reactivity.