The invention discloses a 3D printing method of a sodium alginate / polyvinyl chloride all-physically-crosslinked double-network hydrogel scaffold. According to the technical scheme, the method comprises adding a mixed solution of SA / PVA into gaseous silica to produce thixotropic sol, using an obtained product as a printing material to produce a sol scaffold by 3D printing, freezing the sol scaffold to initiate polymerization of polymer PVA (polyvinyl acetate), fully crosslinking into a single network to produce a preformed gel scaffold, removing to thaw at room temperature, and soaking the preformed gel scaffold in CaCl2 aqueous solution so that SA is fully crosslinked into another gel network to produce the hydrogel scaffold. The method is simple, the production process is short, controlling is simple, production cost is low, the scaffold has good reliability, and the 3D printing method of the sodium alginate / polyvinyl chloride all-physically-crosslinked double-network hydrogel scaffold produces the hydrogel scaffold that is nontoxic, good in mechanical property, high in water absorption and good in biocompatibility.