Laser welding with filler wire has made it possible to improve the economy of welding due to its properties.Therefore,it has broad application prospects in the additive manufacturing and repairing fields.However,the melting behaviors of filler wire seriously affects the stability of welding process and the quality of weld.Based on high-speed camera acquisition technology and welding process test system,this paper focuses on the systematic study of the internal connections between melting behaviors of filler wire and weld quality.The results show that position of wire feeding and the wire feeding speed have a great influence on the melting mechanisms and transfer behaviors of filler wire.According to the change of distance between laser spot and filler wire,transition behaviors of molten metal can be decomposed into globular transition behavior,liquid-bridge transition behavior and spreading transition behavior.The stable welding process and the well-formed deposition layer can be obtained when liquid metal was transferred into welding pool with liquid-bridge.