Abstract: With measuring dynamic temperature change of twin electrode,the heating and melting of twin electrode single arc welding was investigated.Results show that the melting coefficient of twin electrode increases with increasing of welding current,decreasing of coating weight coefficient and decreasing of two-core span,and it is 2-3 times than that of single core electrode.During twin electrode single arc welding,the energy used for heating and melting twin electrode includes resistance heat in core rod and arc heat.The melting of the electrode mainly depends on the arc heat.When the electrode was closely used up,for the current of 200 A,the increase in temperature of TE4303 electrode was approximately 750℃.TE308-16 electrode had high temperature evolution and fast melting rate.The range of temperature field generated by the arc heat in an electrode is generally within 16mm from the electrode end.