A method and device for making metallic glass includes a first step of preparing metal or alloy; a second step of melting metal or alloy into liquid metal; a third step of putting the liquid metal into a boiler and applying pressure into the boiler and the liquid metal being ejected into lines from an outlet located a the lower portion of the boiler; a fourth step of cooling the lines as ejected from the outlet of the boiler in a cooling tank by a quick-flowing coolant; a fifth step of forming straight metallic glass fibers and allowing the metallic glass fibers to be settled to the bottom of the cooling tank; a sixth step of weaving the metallic glass fibers into pieces, and a seventh step of overlapping the pieces into a metallic glass. The lower portion of the boiler is located at a lower level than a surface of the coolant as quickly flowing in the cooling tank.