Abstract: On the basis of oxygen pick-up dynamic analysis in droplet metal,a series of self-made agglomerative fluxes with different basicity indexes were used,by the droplet metal on water cooled copper with no weld pool adopting direct current submerged arc welding,so as to obtain some quality and geometric messages contained in droplet metal for its oxygen pick-up analysis resulted from electrochemical reaction.The results show that,with the increase of slag basicity index,eletrochemical reaction occurring at the interface of slag-metal would be more obvious,and so is the amount of oxygen gaining from electrochemical reactuon.For CaO-Al₂O₃-SiO₂ slag in this study,the extend of oxygen gaining from electrochemical reaction can be almost equal to that from thermo-chemical,therefore it is an in-negligible oxygen induced factor in formulating direct current welding technology or developing high basic index welding consumables.