Based on the problem that the weld of high-speed MAG welding is poorly formed and easy to produce hump bead,the effects of four kinds of one component active agent,Fe,2,O,3,Cr,2,O,3,K,2,O and CaF,2,on the arc stability,metal transfer and appearance of weld of high-speed MAG welding are studied. The results show that four kinds of active agents can increase the arc stability and metal transfer frequency of high-speed MAG welding,among which Cr,2,O,3, corresponds to the most stable arc with reigning arc voltage drops to about 25 V,the K,2,O corresponds to the highest metal transfer frequency,reaching 110 droplets per second. The Fe,2,O,3,Cr,2,O,3, and K,2,O all significantly increase the penetration of high-speed MAG welding weld,optimize the surface appearance of weld,and eliminate hump bead under 1 000 mm/min high speed MAG welding condition.