From JIS, pick device of welding fume is designed. In order to study welding fume forming rate, respectively, this paper collects dust of solid welding wire for MIG welding and flux cored wire for CO2 welding, and points out influence of welding processes and welding parameters on welding fume forming rate, then presents analysis of fume ingredient by Philips X30. It is shown in this paper that there is different characteristics of fume forming rate and fume ingredient under different welding methods and meltdrop transfer.