Abstract: The effects of two filler wire melting methods (laser welding with pre-melted liquid filler by arc and laser welding with filler wire) on the stability of keyhole and the formation of weld seam during laser welding were studied. The influence of filler wire melting method on the quality of welded joints was further studied, and the adaptability of two filler wire melting methods to the welding speed was compared and analyzed. The test results showed that during the laser welding process with pre-melted liquid filler by arc, the keyhole opening size on the surface of the molten pool did not change much, and the keyhole was relatively stable. Because the melted liquid metal was very close to the edge of keyhole, the keyhole opening size on the molten pool surface varied greatly during the laser welding process with filler wire, and keyhole closure on the surface of molten pool was easy to occur. Compared with laser welding with filler wire, during the laser welding process with pre-melted liquid filler by arc, the end of the wire melted by the arc could flow along the molten pool edge, the distance between the liquid metal and keyhole edge was far, the stability of the keyhole was good, the number of weld holes was small.When the welding speed is 8 m/min, weld seams was well during laser welding with pre-melted liquid filler by arc; while the weld seams back surface was not continuous during laser welding with filler wire, and there was a defect of incomplete penetration.