A double-head double-sided high-efficiency friction stir welding device, characterized by comprising: a base; a pair of columns arranged on the base; an upper beam connected with the top ends of the columns, wherein an upper head is arranged on the upper beam; a lower beam connected between the lower ends of the columns, wherein a lower head is arranged on the lower beam and corresponds to the upper head up and down, the columns, the upper beam and the lower beam form a gantry having an integrated structure, and characterised by: at least one worktable connected with a horizontal surface of the base, wherein the worktable is located between the upper head and the lower head, and the worktable and the gantry can relatively move to achieve welding a drive device and a transmission mechanism, wherein the upper head and the lower head are movable by the drive device and the transmission mechanism along an X-axis, a Y-axis and a Z-axis and rotatable along the Z-axis, the upper head and the upper beam, and the lower head and the lower beam are connected through rotary shafts, and welding angle adjustment can be conducted on the upper head and the lower head through the rotary shafts; vision sensors mounted on the upper head and the lower head and used for identifying the weld; and a CNC controller used for controlling operations of the gantry, the upper head, the lower head, the worktable and the vision sensors; and wherein, anti-wear gaskets are arranged at the tail ends of friction stir welding heads of the upper head and the lower head, an external thread is also opened in the friction stir welding head, and a wear-resistant coating is sprayed on the external thread; and wherein raw materials of the anti-wear gasket and the wear-resistant coating comprise: 70-80 percent by weight of tungsten carbide powder, 4-6 percent by weight of alumina fiber, 5-7 percent by weight of titanium dioxide powder, 1-3 percent by weight of vanadium oxide and the balance of graphite powder. a base; a pair of columns arranged on the base; an upper beam connected with the top ends of the columns, wherein an upper head is arranged on the upper beam; a lower beam connected between the lower ends of the columns, wherein a lower head is arranged on the lower beam and corresponds to the upper head up and down, the columns, the upper beam and the lower beam form a gantry having an integrated structure, and characterised by: at least one worktable connected with a horizontal surface of the base, wherein the worktable is located between the upper head and the lower head, and the worktable and the gantry can relatively move to achieve welding a drive device and a transmission mechanism, wherein the upper head and the lower head are movable by the drive device and the transmission mechanism along an X-axis, a Y-axis and a Z-axis and rotatable along the Z-axis, the upper head and the upper beam, and the lower head and the lower beam are connected through rotary shafts, and welding angle adjustment can be conducted on the upper head and the lower head through the rotary shafts; vision sensors mounted on the upper head and the lower head and used for identifying the weld; and a CNC controller used for controlling operations of the gantry, the upper head, the lower head, the worktable and the vision sensors; and wherein, anti-wear gaskets are arranged at the tail ends of friction stir welding heads of the upper head and the lower head, an external thread is also opened in the friction stir welding head, and a wear-resistant coating is sprayed on the external thread; and wherein raw materials of the anti-wear gasket and the wear-resistant coating comprise: 70-80 percent by weight of tungsten carbide powder, 4-6 percent by weight of alumina fiber, 5-7 percent by weight of titanium dioxide powder, 1-3 percent by weight of vanadium oxide and the balance of graphite powder.