This study aims at exploring each stage of the design flow of a cell phone and attempts establishing a time-to-market design method, and the whole study bases on the actual design flow of a flip cover cell phone as an example to analyze the problems encountered during the design process and propose improvements and solutions. All possible issues are attempted and tested during the design process, and the COSMOS is used for the qualitative analysis of the structural strength, and the qualitative analysis result is adopted to expedite the actual practice of the design. The design problems are focused, and the qualitative analysis method and the trial and error method are used to establish a quick method of revising a mold design change and manufacturing conditions. The design flow and the problems encountered in this study can be used as a practical example for education and training to provide reference for new employees, so as to avoid unnecessary mistakes and shorten the design time, and enhance the market competitiveness of the company.