The invention belongs to the technical field of welding equipment, and discloses an embedded double-power supply and double-tungsten electrode welding device and welding method. The welding device comprises an upper gun body, a connecting body connected with the upper gun body, a lower gun body connected with the connecting body, a central tungsten electrode which penetrates through the upper gun body, the connecting body and the lower gun body, a central electrode holder which penetrates through the upper gun body to clamp the central tungsten electrode, an outer annular tungsten electrode, an outer electrode electric conductor, a conductive bolt and an insulating sleeve, wherein the part, in contact with the outer annular tungsten electrode, on the central tungsten electrode is provided with a high temperature resistant insulating material; and the connecting body and the lower gun body are provided with water inlets and water outlets. The central tungsten electrode and the outer annular tungsten electrode in the welding device separately utilize two independent welding power supplies, diversified regulation of composite electric arcs is achieved, the electric arcs of the central tungsten electrode can be compressed through a negative pressure environment created by the electric arcs of the outer annular tungsten electrode, efficient perforation welding is achieved, welding penetration is improved, generated pores are decreased, quality of welding joints is improved, and one-time weld penetration of thick workpieces is achieved.