Abstract: Metal transfer of self-shielded flux cored for vertical down welding condition is studied by using high speed photographic method.The results show that the modes of metal transfer are short circuit transfer,bridging transfer without arc interruption,explosive transfer,and globular transfer.Bridging transfer without arc interruption is the main mode and it also contains two kinds of modes: explosive transfer and surface tension transfer.The characteristic of the former is the explosion of the bridge and the later is that the molten droplet,contacting with molten pool,transferring into the pool by the action of surface tension.As the welding current grows,the droplet becomes small,the frequencies of metal transfer increases,the amount of bridging transfer without arc interruption and explosive transfer increases,and the amount of short circuit transfer decreases.