Abstract: Agglomerated fluxes with different basicity index were used in high-speed welding so as to attain rapid cooled droplet metal under two polarity conditions.The oxygen content of droplet metal was measured using oxygen-nitrogen instrument in order to analyze indirectly metallurgy electrochemical reaction occurred at interface between molten slag and liquid metal in cathode and anode of welding arc.The result showed that it is in the period of droplet growth at the tip of welding wire that an electrochemically gained oxygen was produced in the case of direct current negative polarity whereas an electrochemically lost oxygen in positive polarity.The slag basicity index has great influence upon metallurgy electrochemical reaction.With slag basicity index increasing,the effect of electrochemically induced oxygen which is contrary to thermochemical reaction become more evident for reacting dynamics dependeding on its ion characteristic and therefore it is necessary to be considered as an metallurgy factor.