In this paper, block shear fracture behavior in base metal of fillet-welded connection fabricated with duplex stainless steel (STS329FLD) were investigated through experimental procedures. Main variables are weld lengths in the longitudinal and the transverse directions of applied force. As a result, test specimens failed by typical block shear facture (the combination of tensile fracture and shear-out fracture) in base metal not weld metal. Ultimate strength of the specimens tended to get higher with the increase of the weld lengths.