Control of bead geometry in wire and arc additive manufacturing is significant as it effect the whole manufacturing process. However, the weld beads at arc striking and arc extinguishing area are generally abnormal in which the dynamical process of the weld bead is unstable. In this paper, the abnormal areas in arc striking and arc extinguishing point were investigated. Different parameters were used to make the width and height closed to the middle area in the AS and AE point. A burning-back method was proposed to fill up the slant plane in AE point. Experiments were conducted to study and verify the abnormal areas of the weld bead. And the experimental result indicated that the methods at both ends were available and preferable in the optimization of weld beads.