Chloride diffusion coefficient and water penetration depth of 3 types concrete were studied. The experimental results show that the concrete permeability decreases itself in the order as follow:pure portland cement concrete(C0), concrete added with fly ash(C1), concrete added with both fly ash and silica fume(C2). SEM and microhardness analyses show that the properties of interfacial zone are significantly influenced by silica fume. With the improvement of interfacial zone properties, the permeability especially the Chloride ion diffusivity of concrete significantly decreases.