Abstract:A magnesium substitution design for an automotive seat back rest is carried out.With the magnesium extrusion profiles and the stamping panel integrated,the weight of the seat back rest is reduced by 41.3% and the lightweight goal is achieved.Numerical calculations in comparison with the original structure and the substitution design are performed with finite element software,which ensures that the performance indicators such as the mode,the strength and the stiffness defined by related regulatory requirements are all realized.