Molecular dynamics is utilized to investigate the effect of moisture content on the molecular structure and bonding in the interlayer region between calcium silicate hydrate (C-S-H) and graphene oxide sheet functionalized by deprotonated carboxyl (COO), hydroxyl (C-OH), epoxy (C-O-C) group. The interfacial bonding is dependent on Ca-O-COO, Ca-O-C-(OH), and Ca-O-C-(O)-(C) bond as well as H-bond. These interlayered chemical bonds are sensitive to interlayer water and both of them can be degraded by moisture content increasing, resulting in a decrease in failure strength of GO/C-S-H composite. Among these interlayer chemical bonds, Ca-O-COO bond possesses the highest strength and stability.