In recent years, demand for flexible substrates that connect liquid crystal displays to various devices and substrates, such as tablets, smartphones, game consoles, FA devices, and wearable devices, is increasing. Since these devices needs high signal transmission speed to keep high image quality, the importance of signal integrity measures such as characteristic impedance, transmission characteristics, and radiation noise is increasing. By using Ansys® electromagnetic field analysis and circuit simulator, we can prototype various transmission characteristics of flexible cables and substrates, grasp characteristics when bending, and control impedance characteristics that change with shield materials that suppress radiation. It is possible to understand the characteristics in advance by simulation.