Sodium ion battery (SIB) is a potentially low-cost and safe alternative to the prevailing lithium ion battery (LIB) technology. It has been a great challenge to achieve fast charging and high power density for most SIB electrodes because of the sluggish sodiation kinetics. Here we demonstrate a high-capacity and high-rate SIB anode based on ultrathin layered SnS nanostructures, in which a maximized extrinsic pseudocapacitance contribution is first identified and verified by kinetics analysis. The graphene foam supported SnS nanoarray SIB anode delivers a high reversible capacity of ~1100 mAh g-1 at 30 mA g-1 and ~420 mAh g-1 at 30 A g-1, which even outperforms its Li ion storage performance. The surface-dominated redox reaction rendered by our tailored ultrathin SnS nanostructures may also work in other layered materials for high-performance Na ion storage.