Circular arc flexible forming of sheet metal using plasma arc can be made by combing V-shape curving, the geometrical relationship between circular arc bending part and V-shape is investigated in this paper. In this thesis, the authors analyzed the relationship between a parameter γ and the degree of circular arc smoothness firstly. A simulation program was programmed using the FEA analysis software ANSYS, and the experiments were done. The results showing, when γ = 0.10.12, the forming circular arc is very smooth. The numerical simulation is right for the experimental results.