The effect of silica fume added to basic phase and interface on the interface characteristics and mechanical properties of concrete was studied. Further optimization of mechanical properties of concrete through interface control was also investigated. A key interface parameter for the control on mechanical properties of concrete — G（interface silica fume mass concentration） was proposed. The results show that silica fume added to the interface can significantly improve the mechanical properties of concrete, the promotion of concrete strength is much greater than that of silica fume added in basic phase at lower dosage, can also improve strength and reduce brittleness of concrete at the same time. The parameter G can be used to unify the properties of silica fume in the basic phase and interface, and establish the relationship of silica fume interface strength, which will be of great application value.