Disclosed herein are a tube-type porous scaffold having a double-layered structure for use as an artificial vascular graft and a preparation method thereof. The method comprises (1) dissolving a biodegradable polymer in an organic solvent and mixing the polymer with a porogen so as to provide a polymer/porogen mixture; (2) coating a cylindrical shaft with the polymer/porogen mixture so as to form an inner porous coating layer; (3) preparing a biodegradable polymer gel by dissolving a biodegradable polymer in an organic solvent; (4) spinning down the biodegradable polymer gel in a non-solvent coagulation bath in which the cylindrical shaft having the inner porous coating layer, obtained at step (2), is immersed and rotated to form gel-phase fibers and allowing the gel-phase fibers to wind around the inner porous coating layer of the rotating shaft so as to form an outer polymer fibrous layer; and (5) separating the double-layered porous scaffold, formed on the shaft, from the shaft and removing the organic solvent and the porogen from the scaffold. Since the porous scaffold has a double-layered structure consisting of an inner porous coating layer containing micropores and a gel-phase outer polymer fibrous layer, it has high pore interconnectivity and mechanical strength, which effectively prevents the leakage of blood, and has high cell seeding and proliferation efficiencies, thereby being useful as a tissue-engineered artificial vascular graft.