Abstract: Single arc welding with twin electrode(TE4303) was studied from the welding efficiency and energy saving,microstructure,mechanical properties,and fracture morphology.The results show that melting coefficient and deposition coefficient of TE4303 single arc welding are as two times higher as that of the traditional single electrode(E4303) arc welding.Compared with E4303 arc welding,TE4303 single arc welding can save electrical energy about 20%~30% to melt per unit weight of electrode metal.Meanwhile,its welding heat input is low to get the small fusion ratio.The columnar grains in weld are much slimmer at the same welding current.It is also found that both the compositions and mechanical properties of the deposited metal meet the requirements of standards.The analysis on fracture appearance shows that it is ductile fracture with dimple mode,and the inclusions are oxides which are analyzed by electron probe microscope.