The elastic arm button is commonly used in the structural design of consumer products. The purpose of this study is to find the optimal design parameters of elastic arm button based on two commercial design cases. The finite element method was used to find the stress and deformation of the design structure and the Taguchi method was used to find the optimal design parameters and the quality objective function for optimal design was minimization of stress. The considered control factors included the shape, thickness, width of the button etc. In this case study, the result from the calculated S/N ratios, linear graphs and response graphs of control factors showed that the biggest factor affecting the stress of button is the thickness of the button and the percent contribution was around 53.67%.