The binder surface design is an important prerequisite to ensure the high-quality of panel forming. Therefore, a multi-curvature design method for binder surface based on an improved butterfly optimization algorithm was proposed. Firstly, according to the requirements of drawing process characteristics, the boundary combination template composed of chamfer, straight line and curve in order was established. Then, based on the combination template, a binder surface boundary fitting method based on the improved butterfly optimization algorithm was proposed, and by introducing chaotic mapping to enrich the diversity of initial population and improve the global search ability. At the same time, Gaussian variation strategy was implemented for individuals to enhance the local search ability and improve the convergence speed. Finally, the generated boundary curve segments were grouped and matched, and the corresponding multi-curvature binder surfaces were generated through scanning and guiding. For automotive panel, the multi-curvature binder surface obtained not only meets the requirements of process feature combination,but also ensures the outer contour shape of panel. Numerical simulation and forming tests show that the binder surface designed by this method meets the drawing process requirements and guarantees the forming quality of panel.