Drive line is the surface defect on the automotive panel. In order to investigate the causes and control methods of the drive line, the box-shaped part with curved bottom was designed based on the shape characteristics of automobile panel. Then this part was taken as an experimental model to analyze the causes and forming process of the drive line on its surface. Finally, influencing laws on the drive line from the draw bead, the important forming process parameter, were obtained by the experiments. The results showed that the draw bead has great impact on the drive line. Different setting ways of the draw beads can make good control for the formation, displacement and its direction of the drive line. Besides, it is an important way for setting the draw beads properly to prevent the stamping parts from the formation of the drive line.